Port VideoChannelUtils to MSC3401

[robintown]

As a preparatory task for integrating Element Call into Element Web, the utilities from the VideoChannelUtils file need to be ported to work with MSC3401, in addition to the proprietary io.element.video events that we use today for video rooms. I would suggest putting the MSC3401 versions of these utilities in a file called GroupCallUtils.

Since Element Call is already doing some of the work for us, not all of the utilities need to have MSC3401 versions. The only ones that will be used within the react-sdk, are:

• getVideoChannel (should probably be named getGroupCall, and return the active m.call event)
• useConnectedMembers (needs to take the m.call event as an input in order to find the associated m.call.member events)
• removeOurDevice
• fixStuckDevices

These should all be accompanied by unit tests.

Since these functions will need to inspect m.call and m.call.member events, but the types for them are sitting in the unmerged robertlong/group-call branch of the js-sdk, it's okay if those type declarations get duplicated in the react-sdk. Once we finish merging the group call branch back into mainline, we can remove those redundancies, but we just need something to build off of for the moment.

[weeman1337]

Hi @robintown I wonder how fixStuckDevices is supposed to work. According to the spec there is no last seen per device any more. Instead there is an m.expires_ts for the entire m.call.member state. Maybe you have an idea?

[robintown]

You should still be able to call await client.getDevices(); and then look for the last_seen_ts on each, right? That shouldn't've changed with MSC3401.

[robintown]

Both the io.element.video.member events and the m.call.member events have a single expires_ts value in their content, so the logic should be practically the same