Enabled desktop sharing and discontinue support for Safari versions prior to 12.1, i.e., the ones with no VP8 support

Co-authored-by: Saúl Ibarra Corretgé <saghul@jitsi.org>

Switch to using ontrack for remote tracks, re-use mids/transceivers when remote sources are removed and added.

Co-Authored-By: Saúl Ibarra Corretgé <s@saghul.net>

Use unique session id per TPC.
Translate a=rid to Jingle only when simulcast through RIDs, i.e., ssrc-less simulcast is supported

* Add Edge beta (Chredge) to the list of chromium based browsers.

React Native also supports it now.

* Removes Edge support.

* Removes unused dependency.

jitsi-meet-spot currently supports mobile browsers. A
line should be drawn somewhere but maybe not here.
Chrome iOS does not have navigator.mediaDevices so add
a truthy check before checking for getDisplayMedia.

Chrome 71 does not support inline installs, but has navigator.getDisplayMedia
behind a flag. Support this case.

It's supported in Chrome >= 65.

Safari 11 has `navigator.mediaDevices.ondevicechange` but doesn't define
`navigator.mediaDevices.addEventListener`. 🤦

Fixes: https://github.com/jitsi/lib-jitsi-meet/issues/823

This function helps simplify the code when handling browsers that are pretty
much Chrome in disguise.

- Don't use it on supported browsers
- Make sure no stray timers are left

* Enables adapter for edge.

We were not filtering correctly all unsupported iceServers and an error is thrown and no connection is established.

* Enable desktop sharing for Edge.

Currently when replacing video track with desktop sharing one, doesn't work because of: https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/17528460/
If Edge user joins first and enables desktop sharing it will work when others join. Tried also to use replaceTrack/setTrack as a workaround, but again we hit an error, this time InvalidAccessError.

* Adds the helper function usesAdapter in BrowserCaps.

There is nothing asynchronous about the initialization process (anymore), thus
turn it into a synchronous method.

In addition, WebRTC support is absolute, it cannot change from not being
supported to being supported (as it plreviously could, thanks to Temasys) so get
rid of the ancillary logic to support that.

Last, introduce a way to check if WebRTC is supported in the current
environment: JitsiMeetJS.isWebRtcSupported().

With the update of react-native-webrtc to M67, the ability to stop the camera
when a track is disabled was introduced, so there is no longer a need for doing
a local O/A to remove the track for video muting.

Currently P2P won't succeed on FF because it's not supported by
sdp-interop.

Adds stats and audio levels for Safari. Enables the new getStats API for Firefox, that will get rid of the following warning:
'non-maplike pc.getStats access is deprecated, and will be removed in the near future! See http://w3c.github.io/webrtc-pc/#getstats-example for usage.'

* ref(gum): try to reduce complexity of obtainAudioAndVideoPermissions

Even though I walk through the valley of the shadow of death
I will fear no evil... Reduce indenting and repeated calls to
getting desktop streams by creating a promise chain.

* squash: use arrow func

* squash: move constructor support to helper

* squash: put ff into mediastream constructor check

* squash: ff support media stream constructor

MDN states its been supported since 44. ESR is currently
52.

* squash: rename dsoptions, constant defaults

* squash: move comment about missing tracks error handling

* squash: wrap getUserMediaWithConstraints in promise

* squash: split up av funcs

* squash: hey, some tests...are better than no tests?

lib-jitsi-meet does not get polyfilled for es6 methods.
Using Array.prototype.find will cause breakages in older
browsers, like ie11. The quick fix for now is changing
the find call to be a for-loop. The long term fix will
be discussed soon.

* fix: Fixes version comparison.

* fix(BrowserCapabilities): Searching for the correct version from capabilitiesDB.

* fix(BrowserDetection): Remove unnecessary checks.

In order to include browser capabilities in RTCBrowserType I needed to
refactor RTCBrowserType.