Adds a new event fired when Jitsi Meet shows the feedback prompt.

The conference disconnection process is asynchronous which means there's
no guarantee that there will be CONFERENCE_LEFT event for the old
conference, before the next conference is joined. Because of that we can
end up with two simultaneous calls on the native side which is not
always supported. End the call on CONFERENCE_WILL_LEAVE to fix this
corner case.

Using an array of styles in Firefox causes an error
that triggers jitsi-meet to redirect to a static page.

They generate a bunch of harmless yet confusing error messages and they are not
really useful.

RTCAudioSession is a thin wrapper around AVAudioSession provided by the WebRTC
framework. It makes some use-cases easier, and leads us closer to manual audio
unit management, which we will likely need in the near future.

If a new conference is joined and as a result the current one is terminated,
don't ever attempt to set the audio mode.

Fixes this issue:

Main Thread Checker: UI API called on a background thread: -[UIApplication setExpectsFaceContact:inLandscape:]
PID: 25442, TID: 10886619, Thread name: (none), Queue name: com.facebook.react.ProximityQueue, QoS: 0
Backtrace:
4   JitsiMeet                           0x000000010a0eaadc -[Proximity setEnabled:] + 64
5   CoreFoundation                      0x00000001fea34630 <redacted> + 144
6   CoreFoundation                      0x00000001fe912450 <redacted> + 292
7   CoreFoundation                      0x00000001fe913034 <redacted> + 60
8   JitsiMeet                           0x000000010a4e08e8 -[RCTModuleMethod invokeWithBridge:module:arguments:] + 492
9   JitsiMeet                           0x000000010a4e7a10 _ZN8facebook5reactL11invokeInnerEP9RCTBridgeP13RCTModuleDatajRKN5folly7dynamicE + 248
10  JitsiMeet                           0x000000010a4e776c ___ZN8facebook5react15RCTNativeModule6invokeEjON5folly7dynamicEi_block_invoke + 88
11  libdispatch.dylib                   0x000000010b943824 _dispatch_call_block_and_release + 24
12  libdispatch.dylib                   0x000000010b944dc8 _dispatch_client_callout + 16
13  libdispatch.dylib                   0x000000010b94ce6c _dispatch_lane_serial_drain + 720
14  libdispatch.dylib                   0x000000010b94db60 _dispatch_lane_invoke + 460
15  libdispatch.dylib                   0x000000010b957bfc _dispatch_workloop_worker_thread + 1220
16  libsystem_pthread.dylib             0x00000001fe6490dc _pthread_wqthread + 312
17  libsystem_pthread.dylib             0x00000001fe64bcec start_wqthread + 4

invite post to use application/JSON

changed to .ajax from .post to allow content type to be set

A reducer must always return a state or null to ignore it. When the color scheme
is undefined we should return the previous state.

Both Chrome and Firefox can work without extensions now, so it no longer makes
sense to default to disabling it in Chrome. Moreover, rely on the fact that
undefined is falsey so no actual config needs to be provided.

We are going to implement the invite dialog *inside* the SDK, so there is no
need to have all this machinery anymore.

* fix(large-video): do not show avatar if no url

By default the large video dominant speaker avatar
has an empty src, which will result in a broken
image displaying. There is also disconnect with
non-react code trying to set an undefined src.
To prevent such until local avatar generation
work is done in the future, just don't show the
avatar.

* fix(conference): set the room instance earlier

Set the room instance on APP.conference before triggering
a redux update of the conference being set,, because
middleware can then fire and call methods on APP.conference
that depend on the room being set.

* get local participant directly from store instead of from global

chore(deps): update LJM to get ICE failed notifications

This reverts commit 7c911eca96.

I'm dumb. We need global mode because otherwise lastIndex is not updated in the
regex object, which we rely upon, so this is intentional.

When we are in the default state (ie, not in a meeting) we shouldn't override
the AVAudioSession category and mode. It's a singleton and we might be bothering
other components of the host app which use it.

Updates LJM to 2e1436e20d which includes
the ICE failed notification logic.

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