Focus the thread panel when clicking on an item in the TAC (#12410)

* Focus the thread panel when clicking on an item in the TAC

actually the 'close' button in the threads panel as it's the only
interactive element: we can improve this later when we use landmarks
& generally have better a11y.

* Undo minor refactoring

as none of it is test3ed, it's not worth it.

* add unit test

* Add matrixchat tests

* Needs awaits

* ts-ignore

* Fix test (I think...)

* Remove unnecessary value set

* Not how assignments work

src/components/views/spaces/threads-activity-centre/ThreadsActivityCentre.tsx

@@ -159,6 +159,7 @@ function ThreadsActivityCentreRow({ room, onClick, notificationLevel }: ThreadsA
                     show_room_tile: true, // make sure the room is visible in the list
                     room_id: room.roomId,
                     metricsTrigger: "WebThreadsActivityCentre",
+                    focusNext: "threadsPanel",
                 });
             }}
             label={room.name}