Creating a new async prosody http wrapper.

feat(calls): Adding missed call event triggering.

* ref(device-selection): do not override var that is not reference again

* ref(device-selection): do not override var that is not reference again

* ref(device-selection): always update known devices on device list update

* ref(device-selection): replace call to get devices from legacy to redux

* ref(device-selection): remove unused device list state from mediaDeviceHelper

* ref(device-selection): update store before updating UI

There doesn't seem to be a strong need for the initialized React
Component state in BaseApp so remove/delete it.

BaseApp does all the heavy-lifting related to creating the redux store,
navigation, and so on.

App currently handles URL props and actually triggering navigation based on
them.

Move it away from AbstractApp into an auxiliary function. In addition, introduce
a new `getServerURL` function which gets the configured server URL and defaults
to meet.jit.si as before.

It was never used in practice, and it would be very cumbersome to use, since it
would have to bcreated with all the middlewares and reducers we need. After
discussing this with Lyubomir, we are confident this is not going to be needed
so it can go.

Unfortunately, as the Jitsi Meet development evolved the routing mechanism
became more complex and thre logic ended up spread across multiple parts of the
codebase, which made it hard to follow and extend.

This change aims to fix that by rewriting the routing logic and centralizing it
in (pretty much) a single place, with no implicit inter-dependencies.

In order to arrive there, however, some extra changes were needed, which were
not caught early enough and are thus part of this change:

- JitsiMeetJS initialization is now synchronous: there is nothing async about
  it, and the only async requirement (Temasys support) was lifted. See [0].
- WebRTC support can be detected early: building on top of the above, WebRTC
  support can now be detected immediately, so take advantage of this to simplify
  how we handle unsupported browsers. See [0].

The new router takes decissions based on the Redux state at the time of
invocation. A route can be represented by either a component or a URl reference,
with the latter taking precedence. On mobile, obviously, there is no concept of
URL reference so routing is based solely on components.

[0]: https://github.com/jitsi/lib-jitsi-meet/pull/779

It can be that deviceChangeListener is never defined because
the isDeviceList call never completes. On hangup, that would
cause an error to be thrown within lib-jitsi-meet because of
an attempt to remove an undefined event handler. That is
what happens on Safari right now.

[RN] Update audio route selection copy

Detects msid changes and signals them, part of fixing start A/V muted using Firefox.

When replace track is called in JitsiConference, there is no
guarantee a videoType update will come in presence before
the track added event. This can lead to the situation in
LargeVideoManager where an update is called with a track
with an undefined videoType.

* fix(connection): reload immediately on possible split-brain

There isn't an explicit way to know when a split brain
scenario has happened. It is assumed it arises when an
"item-not-found" connection error is encountered early
on in the conference. So, store when a connection has
happened so it be calculated how much time has
elapsed and if the threshold has not been exceeded
then do an immediate reload of the app instead of
showing the overlay with a reload timer.

* squash: rename isItemNotFoundError -> isShardChangedError

This will make it easier to support horizontal, vertical, and
tile layout filmstrip by reducing the css overriding needed
for tile layout.

feat(device-selection): new icon for audio output

ref(toolbar): remove use-new-toolbox class