Fix/websocket drops keeping bolts

Merge branch 'fix/websocket-drops-keeping-bolts' of github.com:RocketChat/Rocket.Chat.Android into fix/websocket-drops-keeping-bolts

preventing multiple threads inconsistently creating multiple websocket
threads for the same host and thus avoiding connecting to server multiple times unnecessarily.
Changed network changing fallback implemention to try to reconnect to
automatically and force-invalidating the session token before doing
this.

Avatar caching improvements

A change of network type will now show a snackbar when a failure occur which will trigger a websocket reconnection flow

Solve avatar caching and add SVG support