Feature: SharePlay

[insidegui]

There's still a lot to be done in order for this to be included in a non-beta version of the app:

Must-haves

• [ ] Starting the playback of a different session than the one that's currently playing after initiating SharePlay should switch all participants to that session
• [ ] The same scenario above should probably warn the user before proceeding, to prevent accidental disturbances to all participants in the session

Nitpicks and nice-to-haves

• [ ] I've noticed that the speed button in the player doesn't reflect speed changes coming from the SharePlay session
• [ ] Could we add the ability for participants to add bookmarks in such a way that they sync to all participants? 🤔

There are probably unknown issues and edge cases that we'll only learn about once this is actually being used by people