Fixes https://github.com/vector-im/riot-web/issues/14179
Disclaimer: this is all of the horrible because it's not meant to be here. Invites in general are likely to move out of the room list, which means this is temporary. Additionally, the communities rework will take care of this more correctly. For now, we support the absolute bare minimum to have them shown.
For example, if you only have 3/10 rooms required for the default then resize smaller, we should have a 'show more' button.
This works by changing the rendering to be slightly more efficient and only looping over what is seen (renderVisibleTiles(), using this.numTiles in place of tiles.length) and using a new setVisibleTilesWithin() function on the layout. Previously resizing the 3/10 case would be setting visibleTiles to ~8 instead of ~1 like it should (because the getter returns a default).
`setKnownRooms` is called to regenerate the room list, and if we don't take the sticky room out of the equation we end up with the room being duplicated. So, to make this easy, we simply remove the sticky room and handle it after the fact.
This small check just ensures that we aren't about to blindly accept that the calling code knows what it is doing. There are some unknown cases where NewRoom gets fired for rooms we already know about, so in those cases we just change it to a PossibleTagChange which is what the caller likely intended.
Many of the edge cases are unknown, though this can happen for an invite being accepted (for example). It's easier to handle it here instead of tracking down every single possibility and fixing it higher up.
When a new room is added there's a fairly good chance that the other events being dispatched will happen in the middle of (for example) the room list being re-sorted. This commit wraps the entire handleRoomUpdate() function for the underlying algorithms in a lock so that if we're unlucky enough to get an update while we're sorting (as the ImportanceAlgorithm splices out what it is sorting) we won't scream about invalid index errors.
We have to do a bit of a dance to return the sticky room to the list so we can remove it, if needed, and ensure that we generally swap the rooms out of the list.
This reverts earlier changes made to textForEvent as they are no longer needed.
This also implements an entire tree of textForEvent-like behaviour as the previews need to be different, which is easiest done with its own stack.
Smaller handle width, small shadow on the top of the show more button if there's more rooms to be shown. The resize handle also only shows when you're hovering in the area now.
The original design called for the shadow to show up only if the user is cutting a tile or dragging, however that is complicated implementation-wise. For speed and encouraging a dogfooding pattern we're going ahead with this behaviour instead.
