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.

The lobby feature adds the possibility to lock a meeting and only allow people in after virtually knocking and going through formal approval

Avoid importing components, which are not yet implemented on mobile.

- Invite funcionality (altogether)
- Recording
- Live streaming
- Meeting name
- Meeting password

* Add dialog to set the E2EE key
* Use the Redux action / middleware to update the key even when set through the
  hash parameter
* Cleanup URL after processing the key so it's not recorded in browser history

This reverts commit 953f838a2a.

* Accessibility: Make the native toolbox item communicate that it is a button.

* Accessibility: If an item is toggled, mark it as selected for accessibility

* Accessibility: Make the toolbox a toolbar for accessibility

* Accessibility: Mark the bottom sheet as a menu for accessibility

* Fix typo, AccessibilityRole, not AccessibleRole

* Statement fix

* Appease the linter

* Fix linting errors for real this time

Some CSS fixes are also included.

* Expose toggle buttons better via ARIA

* Wire up the divs/li as role=button as per ARIA patterns

* Add flow annotations to appease the linter

* For role=button use aria-pressed not aria-checked

This reverts commit faf24ca7ec.

This reverts commit 08f55ccb94.

Add ability to invite users which will use the share sheet or dialog
dynamically.

- re-add thepand icon, shaped like a pill
- round top corners

Regresssion from bd8a7edbd2.

When the toolbar buttons are overridden with URL parameters, our computed set of
buttons will be wrong. Thus, compute it every time and check for the
differences.

- Adds the ability to share video as a "PiP" when screenshare is in progress.
- Add a method for creating a local presenter track.
- Make sure isLocalVideoTrackMuted returns the correct mute state when only screenshare is present.
- Make sure we get the updated window size of the window being shared before painting it on the canvas.
- Make sure we check if the shared window has been resized

* Add shortcut key for toggle tile view

* Toggle tile view shortcut - undo main-enGB.json

* Add analytics

* Use already defined toolbar translations

- simplify initialization procedure
- set user display name as the Etherpad name\
- use SharedDocumentButton

This refactors all handling of audio-only and last N to 2 features in preparation
for "low bandwidth mode".

The main motivation to do this is that lastN is a "global" setting so it helps
to have all processing for it in a single place.