Service-agnostic music integration

Problem

Many of the most popular Discord bots exist to share music across voice channels. Having first-class support for sharing music in Fluxer would be greatly appreciated, particularly if it doesn't lock you to a particular streaming service.

Proposed solution

Next to the screen share button, there could be a Share Music button. When pressed (or maybe in settings, a default application could be selected), the user could choose an application that is playing music. A new audio stream would be opened in the voice channel that is dedicated to that application, and users could adjust volume on their end, just like with another user. There might be a limit of one music stream per channel, but that may not be necessary.

Notes (optional)

I would love to work on this. I am primarily a frontend developer, but I could struggle through the backend to make it work. If you are a backend developer with more than 0 experience in LiveKit and/or erlang and would like to help, please let me know! Backend code could probably be borrowed from the existing screenshare logic, but I haven't looked into it. The downside to this approach is that users can't queue new music. I think the only way to get around that would be service-specific APIs, which would make this a much heavier lift. I won't work on this until the green light is given after refactor is merged.