This version is not supposed to properly work, this is a work in
progress.
Main changes:
* Completely removed the PTT logic (for simplicity, it could be
introduced later).
* Abstracted away the work with the media devices.
* Defined confined interfaces of the affected components so that they
only get the data that they need without importing Matris JS SDK or
LiveKit SDK, so that we can exchange their "backend" at any time.
* Started using JS/TS SDK from LiveKit as well as their React SDK to
define the state of the local media devices and local streams.
