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/dispatcher/payloads/ViewRoomPayload.ts

@@ -24,6 +24,8 @@ import { IOpts } from "../../createRoom";
 import { JoinRoomPayload } from "./JoinRoomPayload";
 import { AtLeastOne } from "../../@types/common";
 
+export type FocusNextType = "composer" | "threadsPanel" | undefined;
+
 /* eslint-disable camelcase */
 interface BaseViewRoomPayload extends Pick<ActionPayload, "action"> {
     action: Action.ViewRoom;
@@ -61,5 +63,6 @@ export type ViewRoomPayload = BaseViewRoomPayload &
         // the number of API calls required.
         room_id?: string;
         room_alias?: string;
+        focusNext: FocusNextType; // wat to focus after room switch. Defaults to 'composer' if undefined.
     }>;
 /* eslint-enable camelcase */