Improve UX of RoomSettings

[ara4n]

The sister-bug for #5476, which has ended up being mostly about UserSettings - although has some discussion of how UserSettings could be updated to match...

[turt2live]

ftr the tabbed settings stuff I'm (slowly) working on plans to address this by going through a similar review process. The reason for picking on UserSettings first is because it is the most complex and complained about.

[aaronraimist]

Probably fixed by redesign otherwise a more specific issue should be opened or added to #8207