Group Watch feature

[tmess11]

Problem to solve

Users unable to watch streams together in a group.

Proposal

Once multiple stream support is implemented, allow users to create groups so that they can synchronize both the streams and what channel is being watched together.

Further details

Allow for creation of the group via the UI as well as adding users to the group from the UI. Allow all users in the group to add users to the group. Allow users to leave the group. Allow users to share group via link for others to join.