Showing the modal earlier is weird because it will be closed as soon as we
connect. Also, we don't know if we are going to be alone until we join.

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

Use a dimensions detecting root component. The Dimensions module does not
measure the app's view size, but the Window, which may not be the same, for
example on iOS when PiP is used.

Also refactor the aspect ratio wrap component since it can be taken directly
from the store.

Last, remove the use of DimensionsDetector on LargeVideo and TileView since they
occupy the full-screen anyway.

Fixes PiP mode on iOS.

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

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

The welcomePageEnabled and pictureInPictureEnabled props on mobile have been
converted to feature flags.

When in a conference, try to enter PiP when pressing the back button. If this is
not possible (because it's unsupported, not enabled, etc.) fall back to the
previous behavior of simply hanging up.

This PR changes the logic for connecting / disconnecting conferences. Instead of
doing it in mount / unmount events from the Conference component, it moves the
logic to the appNavigatee action.

This fixes a regression introduced in 774c5ecd when trying to make sure the
conference terminated event is always sent.

By moving the logic to appNavigate we no longer depend on side-effects for
connecting / disconnecting, and the code should be more maintainable moving
forward.

An improvement to this is the concept of sessions, which, while not tackled
here, was taken into consideration.

Dear reader, I'm not proud at all of what you are about to read, but sometimes
life just gives you lemons, so enjoy some lemonade!

Joining a conference implies first creating the XMPP connection and then joining
the MUC. It's very possible the XMPP connection was made but there was no chance
for the conference to be created.

This patch fixes this case by artificially genrating a conference terminated
event in such case. In order to have all the necessary knowledge for this event
to be sent the connection now keeps track of the conference that runs it.

In addition, there is an even more obscure corner case: it's not impossible to
try to disconnect when there is not even a connection. This was fixed by
creating a fake disconnect event. Alas the location URL is lost at this point,
but it's better than nothing I guess.

Adds 1 liner notifications to mobile. Only the title is displayed. In
case the title is missing there's a fallback to the description.

🔥🔥🔥