* feat(Android): implement ConnectionService

Adds basic integration with Android's ConnectionService by implementing
the outgoing call scenario.

* ref(callkit): rename _SET_CALLKIT_SUBSCRIPTIONS

* ref(callkit): move feature to call-integration directory

* feat(ConnectionService): synchronize video state

* ref(AudioMode): use ConnectionService on API >= 26

Not ready yet - few details left mentioned in the FIXMEs

* feat(ConnectionService): add debug logs

Adds logs to trace the calls.

* fix(ConnectionService): leaking ConnectionImpl instances

Turns out there is no callback fired back from the JavaScript side after
the disconnect or abort event is sent from the native. The connection
must be marked as disconnected and removed immediately.

* feat(ConnectionService): handle onCreateOutgoingConnectionFailed

* ref(ConnectionService): merge classes and move to the sdk package

* feat(CallIntegration): show Alert if outgoing call fails

* fix(ConnectionService): alternatively get call UUID from the account

Some Android flavours (or versions ?) do copy over extras to
the onCreateOutgoingConnectionFailed callback. But the call UUID is also
set as the PhoneAccount's label, so eventually it should be available
there.

* ref(ConnectionService): use call UUID as PhoneAccount ID.

The extra is not reliable on some custom Android flavours. It also makes
sense to use unique id for the account instead of the URL given that
it's created on the per call basis.

* fix(ConnectionService): abort the call when hold is requested

Turns out Android P can sometimes request HOLD even though there's no
HOLD capability added to the connection (what!?), so just abort the call
in that case.

* fix(ConnectionService): unregister account on call failure

Unregister the PhoneAccount onCreateOutgoingConnectionFailed. That's
before the ConnectionImpl instance is created which is normally
responsible for doing that.

* fix(AudioModeModule): make package private and run on the audio thread

* address other review comments

* fix(local-recording): allow config override to enable

Config overrides are not set until some time after
APP_WILL_MOUNT has completed and not in the same execution
context as when APP_WILL_MOUNT is called. So instead
choose recording controller initialization at a later time.
The time chosen is after conference join because the
controller needs the conference instance to work.

* remove redundant conditional check

- remove unneeded dialog (it's taken care of by StartRecordingDialogContent)
- pass correct props so integrations (Dropbox) show up

While Apple doesn't want to allow us to enable Dropbox, it's good to have it
available for testing.

There was a missing delegate method call into RNGoogleSignIn, which fixed this.

- unpin participant (if the local one was pinned it would remain)
- close any dialog (except if authentication is pending)

Co-authored-by: DimaG <dgeorgiev06@gmail.com>

Analytics is erroring when unpinning because the logged
event sends null for the objectId. The objectId should
be the id of the person getting unpinned.

This feature is intended for spot. Spot can have an
HDMI -> usb adapter hooked up to it. In that case,
attempting to screenshare should use that adapter
as a screensharing source. Jitsi-Meet should pass
a configured screenshare source into lib-jitsi-meet
so it can be used as a source.

The class name is similar to the one used for the mute button and is used by the tests to locate and click the button.

Provide a default and builtin default implementation which finishes the
Activity, same as before.

What this PR removes is the ability to provide a custom default handler because
applications can already take this decision when calling `onBackPressed`. In
addition, make `onBackPressed` return `void` because it's virtually impossible
for it to return `false` (that would mean that there is no
`ReactInstanceManager`, which means there is no app to begin with).

In addition, remove the use of `BackAndroid` since `BackHandler` contains an iOS
shim now.

We no longer need it since Rect 16 takes care of passing the context around.
It's also deprecated: https://atlaskit.atlassian.com/packages/core/layer-manager

Instead of handling the side effect of navigating to another
url from within componentWillReceiveProps, try to match the
same logic instead in componentDidUpdate.

Touch feedback manifests in some ugly black border bleeding out of the thumbnail
itself. Since we already provide feedback (be that by adding the blue border in
case of pinning, or showing the menu in case of long press) the perception is
the same, without the graphical glitch.

- Reset some state on the singletons conference
  and VideoLayout.
- Add a way for LocalVideo to clean itself up
  by sharing logic with the other SmallVideos.
- Add clearing of chat messages so they don't
  linger.
- Remove some UI event listeners.

componentWillMount is a deprecated lifecycle method;
componentDidMount should be used to kick off things
like ajax. In the case of the _App hierarchy, a promise
chain is used to perform initialization, and it is
first started in the constructor by initializing
storage. However, by the time storage is initialized,
resolving the first promise, _App has already mounted.
So, move it all to the componentDidMount lifecycle.

The package now requires using a ModalTransition component
to handle animations. The existing DialogContainer component
has been split into native and web implementations to support
this change.

Apple rejected our app on account of requiring Dropbox not being acceptable. Oh
well! Disable it until we find a way around it. Sigh.

It's possible for the YouTube api to return zero broadcasts
or broadcasts without any streams--streams are what are
associated with stream keys. In this case, instead of showing
an empty selector or no selector, show a message with a link
to where the stream key can be obtained.

Provide a client-side notice if the YouTube live stream key
looks like it might be in the wrong format. Normally the
stream key looks like 4 groups of 4 numbers and letters,
each separated by a dash. The warning does not block submission
in case YouTube changes their stream key format.