Activity.enterPictureInPictureMode method must be invoked synchronously
on userLeaveHint callback in order to be sure that the current Activity
is still visible (does not transit to PAUSED state). Previously if the
asynchronous processing would be delayed enough for the Activity to go
into the PAUSED state it will be too late to go into the PiP mode.

* Button conditionally shown based on if the feature is enabled and available
* Hooks for launching the invite UI (delegates to the native layer)
* Hooks for using the search and dial out checks from the native layer (calls back into JS)
* Hooks for handling sending invites and passing any failures back to the native layer
* Android and iOS handling for those hooks

Author: Ryan Peck <rpeck@atlassian.com>
Author: Eric Brynsvold <ebrynsvold@atlassian.com>

Activity.enterPictureInPictureMode can fail for a couple of reasons
mentioned in the JSDoc:

"The system may disallow entering picture-in-picture in various cases,
including when the activity is not visible, if the screen is locked or
if the user has an activity pinned."

It seems to be safe to assume that those cases will be caught by
a RuntimeException handler (only RuntimeExceptions can be left without
explicit catch block).

Anyway the root cause for problems is the fact that the current process
for going to the picture in picture mode is not synchronised with
Activity's lifecycle. On Activity's "userLeaveHint" callback we dispatch
async task to the JS code which only then after dispatching some more
stuff eventually call native method that enter PiP. In case we spend too
much time on the JS side and the Activity goes to PAUSED state the call
will fail with IllegalStatException: "activity is not visible",
"activity is paused" etc. This means with this fix the app will not
crash, but we'll see it sometimes not go to the PiP mode as expected.

On Android the files will be copied to the assets/sounds directory of
the SDK bundle on build time. To play the "asset:/" prefix has to be
used to locate the files correctly.

On iOS each sound file must be added to the SDK's Xcode project in order
to be bundled correctly. To playback we need to know the path of the SDK
bundle which is now exposed by the AppInfo iOS module.

Adds Nat64InfoModule which resolves IPv6 addresses for IPv4 addresses
in IPv6 only network where jitsi-meet deployment does not provide any
IPv6 addresses as ICE candidates.

Adds base/sounds feature which allows other features to register a sound
source under specified id. A new SoundsCollection component will then
render corresponding HTMLAudioElement for each such sound. Once "setRef"
callback is called by the HTMLAudioElement, this element will be added
to the Redux store. When that happens sound can be played through the
new 'playSound' action which will call play() method on the stored
HTMLAudioElement instance.

The new libwebrtc.jar contains an extra unused class file, when proguard is enabled result in the following warning:

org.chromium.build.BuildHooksAndroidImpl: can't find superclass or interface org.chromium.build.BuildHooksAndroid

java.lang.RuntimeException: Tried to access a JS module before the React instance was fully set up. Calls to ReactContext#getJSModule should only happen once initialize() has been called on your native module.
	at com.facebook.react.bridge.ReactContext.getJSModule(ReactContext.java:102)
	at com.rnimmersive.RNImmersiveModule.emitImmersiveStateChangeEvent(RNImmersiveModule.java:74)
	at org.jitsi.meet.sdk.JitsiMeetView.onWindowFocusChanged(JitsiMeetView.java:504)
	at android.view.View.dispatchWindowFocusChanged(View.java:10257)
	at android.view.ViewGroup.dispatchWindowFocusChanged(ViewGroup.java:1193)
	at android.view.ViewGroup.dispatchWindowFocusChanged(ViewGroup.java:1197)
	at android.view.ViewGroup.dispatchWindowFocusChanged(ViewGroup.java:1197)
	at android.view.ViewGroup.dispatchWindowFocusChanged(ViewGroup.java:1197)
	at android.view.ViewGroup.dispatchWindowFocusChanged(ViewGroup.java:1197)
	at android.view.ViewGroup.dispatchWindowFocusChanged(ViewGroup.java:1197)
	at android.view.ViewGroup.dispatchWindowFocusChanged(ViewGroup.java:1197)
	at android.view.ViewRootImpl$ViewRootHandler.handleMessage(ViewRootImpl.java:3602)
	at android.os.Handler.dispatchMessage(Handler.java:102)
	at android.os.Looper.loop(Looper.java:154)
	at android.app.ActivityThread.main(ActivityThread.java:6119)
	at java.lang.reflect.Method.invoke(Native Method)
	at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)

Updates react-native-webrtc to get rid of Java 8 requirement for
the Android app.

This only works automatically on Android >= 8. On other platforms / versions, it
relies on the SDK user on implementing a "reduced UI" mode and reacting to the
"request PIP" delegate method.

On Android we go into "immersive mode" when in a conference, this is our way of
being full-creen. There are occasions, however, in which Android takes us out of
immerfive mode without us (the application / SDK) knowing: when a child activity
is started, a modal window shown, etc.

In order to be resilient to any possible change in the immersive mode, register
a listener which will be called when Android changes it, so we can re-eavluate
if we need it and thus re-enable it.

It was recently introduced in WebRTC, so we we need to enable it project wide.
As for what features are supportd, see:
https://developer.android.com/studio/write/java8-support.html

The documentation states this is possible, so make sure we handle such errors.

Ref:
https://developer.android.com/reference/android/provider/Settings.html#ACTION_APPLICATION_DETAILS_SETTINGS

Also remove mavenLocal since we don't need it.

Android Oreo (API level 26) is supported since React Native 50.

Upstream lacked a CocoaPods podspec file, PR:
https://github.com/DylanVann/react-native-locale-detector/pull/3

Due to the difference in nature, the iOS and Android implementations are
completely different:

iOS: MPVolumeView is used, which allows us to place a button which will launch a
native route picker provided by iOS itself. This view is different depending on
the iOS version, with the iOS 11 version being more complete.

Android: A completely custom component is used, which displays a bottom sheet
with the device categories, not devices individually. This is akin to the sheet
in the builtin dialer.

Android Studio won't build the app otherwise. Since the gradle plugin 3.0 beta7,
the minimum supported build tools version is 26.0.2, so set it to that. Also
bump compileSdkVersion to 26 since they need to match (in the major number, that
is).

The target API is still 25. Android Oreo (26) brought some changes in overlay
permissions which I haven't figured out yet.

* Javadoc introduced @code as a replacement of <code> and <tt> which is
  better aligned with other javadoc tags such as @link. Use it in the
  Java source code. If we switch to Kotlin, then we'll definitely use
  Markdown.

* There are more uses of @code in the JavaScript source code than <tt>
  so use @code for the sake of consistency. Eventually, I'd rather we
  switch to Markdown because it's easier on my eyes.

* Xcode is plain confused by @code and @link. The Internet says that
  Xcode supports the backquote character to denote the beginning and end
  of a string of characters which should be formatted for display as
  code but it doesn't work for me. <tt> is not rendered at all. So use
  the backquote which is rendered itself. Hopefully, if we switch to
  Markdown, then it'll be common between JavaScript and Objective-C
  source code.

It provides access to the app's display name and version.

* Regardless of whether the SDK client/consumer employs
  JitsiMeetActivity or JitsiMeetView, default to finishing the
  associated Activity upon invoking the back button (which is what
  Activity#onBackPressed() is documented to do).

* Do not break the public API of JitsiMeetView and, thus, Jitsi Meet SDK
  for Android.

If the JS side chooses to not handle the back button press call
'super.onBackPressed()' to close the app.

Don't require autofocus because that prevents the app from appearing in
Google Play Store for some devices.

Don't require camera for the same reason but also because camera/video
is not a mandatory feature of the app, it's merely likely very
desirable.

The class ReflectiveOperationException used in ExternalAPIModule was
introduced in API level 19.