From now on, webchat can only be activated for local videos.
It will never be displayed on remote videos.
This is because an incompatibility with a new feature (webchat per channel).
Moreover this feature was very limited: the webchat was not shared with the remote instance (this will probably be achieved in a future release).
* init some shared functions (videoHasWebchat, parseConfigUUIDs)
* api/room: checking that video has live enabled
* fix promise handling in initChat function
* removing some 'use strict' that are no more necessary in typescript
