- Remove external install dialogs and fix related screensharing error handling.
- Remove obsolete options from config.js and from configWhitelist.js

saghul: torture tests also need it.

Up until now we relied on implicit loading of middlewares and reducers, through
having imports in each feature's index.js.

This leads to many complex import cycles which result in (sometimes) hard to fix
bugs in addition to (often) breaking mobile because a web-only feature gets
imported on mobile too, thanks to the implicit loading.

This PR changes that to make the process explicit. Both middlewares and reducers
are imported in a single place, the app entrypoint. They have been divided into
3 categories: any, web and native, which represent each of the platforms
  respectively.

Ideally no feature should have an index.js exporting actions, action types and
components, but that's a larger ordeal, so this is just the first step in
getting there. In order to both set example and avoid large cycles the app
feature has been refactored to not have an idex.js itself.

* ref: disable ICE restart by default

The reason for that it's currently causing issues with signaling when
Octo is enabled. Also when we do an "ICE restart"(which is not a real
ICE restart), the client maintains the TCC sequence number counter, but
the bridge resets it. The bridge sends media packets with TCC sequence
numbers starting from 0.

The 'enableIceRestart' config option can be used to force it, but it's
not recommended.

This will let us enable/disable the feature based on environment/deployment

* Adds an option to set email through iframe API init and to stats.

* Simplifies configuring email and displayName in stats.

Removes enableStatsID as not needed as when off we are sending as callstats id xmpp resource which is unique per call and id must be something that sticks between calls (callstatsUsername).

* Adds email and displayName in stats config for mobile.

* chore(deps): Updates lib-jitsi-meet to latest dd31f0a.

* Removes enableStatsID from config and whitelist.

iOS 10 crashes, so don't use it there, in any case.

Currently only 2 options are implemented, mainly aimed at helping troubleshoot
audio related problems:

- Disable native call integration (it disables CallKit / ConnectionService)
- Disable P2P

None of them work on mobile.

They never worked on mobile and pose an impediment for makinf config.js more
future proof. Specially if we want to move to a non-executable form of
configuration.

For now all keys are whitelisted.

It crashes like hell. See:
https://bugs.chromium.org/p/webrtc/issues/detail?id=11002

We try to load the configuration with every room change, even when there is no
room. There is a bad (corner) case: when we have no config cached (first boot or
wiped app data). In such case the user is trapped in an infinite loop because we
require the config to show the welcome page, oh well.

Pretend we have a configuration by creating the most minimal one to at least get
to the welcome page.

React Native doesn't define __filename nor __dirname so do it artisanally. In
addition, this helps with centralizing the configuration passed to loggers.

It was added for
3ea2f00578
over 2 years ago. That's long enough!