Be able to see a list of the latest threads in a room

### Your use case

#### What would you like to do?

See a list of threads in the room, similar to Element Web's Threads sidebar.

#### Why would you like to do it?

So I can go back through old threads quickly without having to scroll through the timeline.

#### How would you like to achieve it?

Probably a menu item in the room's details. Next to "Pinned messages".

### Have you considered any alternatives?

_No response_

### Additional context

This was requested by a FOSDEM staff member :)

### Are you willing to provide a PR?

No