The dynamic size of it was causing trouble. Fix it by setting a fixed PiP window
size (150px) which makes it consisstent with what we have on Android.

Fixes: https://github.com/jitsi/jitsi-meet/issues/6562

We are downloading code off the Internet and executing it on the user's device,
so run it sandboxed to avoid potential bad actors.

Since it's impossible to eval() safely in JS and React Native doesn't offer
something akin to Node's vm module, here we are rolling our own.

On Android it uses the Duktape JavaScript engine and on iOS the builtin
JavaScriptCore engine. The extra JS engine is *only* used for evaluating the
downloaded code and returning a JSON string which is then passed back to RN.

See: https://github.com/jitsi/jitsi-meet/issues/4720

The subsystem is set to the bundle ID and the category to "JitsiMeetSDK".

These provide the ability to integrate the SDK with some other application
loggers.

At the time this was written we use Timber on Android and CocoaLumberjack on iOS.

In addition to the integration capabilities, a LogBridge React Native module
provides log transports for JavaScript code, thus centralizing all logs on the
native loggers.

This commit refactors device selection (more heavily on iOS) to make it
consistent across platforms.

Due to its complexity I couldn't break out each step into separate commits,
apologies to the reviewer.

Changes made to device handling:

- speaker is always the default, regardless of the mode
- "Phone" shows as a selectable option, even in video call mode
- "Phone" is not displayed when wired headphones are present
- Shared device picker between iOS and Android
- Runtime device updates while the picker is open

It causes a compiler error in Xcode 11 because it doesn't know how to parse it.

At the moment it includes:

- display name
- email
- avatar URL

This information is used *only* if no token was specified.

The welcomePageEnabled and pictureInPictureEnabled props on mobile have been
converted to feature flags.

They may contain sensitive information.

This reverts commit 603d161788.

It's possible a CallKit event arrives when the React Bridge has been torn down
and there is an assert that checks this. In order to avoid a crash, just skip
the event.

Replace the Swift array with an Objective-C one, since it's going to store
Objective-C objects and not Swift objects (or Swift objects which inherit from
NSObject, which is equivalent).

This avoids the need for JMCallKitEventListenerWrapper entirely, since an
NSArray can store NSObjectProtocol objects, unlike a Swift array, which prompted
the creation of the wrapper in the first place.

The SDK will now search for an asset called "CallKitIcon" on the main bundle,
and fallback to a built-in asset it it's not there, allowing SDK users to
customize it by just adding asset with that name.

When CallKit is enabled / disabled, a new CXProvider must be created in order to
not confuse CallKit (it misbehaves otherwise).

Ever since we switched to handling track events instead of mute actions this has
been dead code. It was also added in the wrong place, since it's responsibility
of the JS code to solve the ping-pong problem.

NSURLConnection sendSynchronousRequest is deprecated since iOS 9. Replace the
method by whjat's currently on RN master, which implements a modern alternative.

This new version comes with an updated JSC runtime, so we no longer need to
depend on the updated version ourselves.

The app should always provide them.

Consolidate all failure cases into a single one: CONFERENCE_TERMINATED. If the
conference ended gracefully no error indicator will be present, otherwise there
will be.