TagPanel - make filtering quick (by caching rooms and users associated with a group) and accurate (by loading the most recent data when selecting a filter)

[lukebarnard1]

• Pull /users and /rooms for groups that the user in joined to when TagPanel RoomList mounts. Prefetch group data for all joined groups when RoomList mounts matrix-org/matrix-react-sdk#1686
• Optimise for many rooms being displayed. This might be quite generic performance work on the room list.
  • So far, we have at least optimised for selecting tags: Improve performance of tag panel selection (when tags are selected) matrix-org/matrix-react-sdk#1687
  • We have also optimised to cache isConfCallRoom, which inspects the other members of the room but only needs to calculated once per-room. Cache isConfCallRoom matrix-org/matrix-react-sdk#1693
• Pull /users, /rooms and the group profile when the user filters by that group

[ara4n]

This is option 6 of https://docs.google.com/document/d/1GzwhGdnWWMENYOaXMFP8CD-M9ny1vznxHnNqT3I3NZI/edit fwiw.

[t3chguy]

The TagPanel is gone