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

playwright/e2e/spaces/threads-activity-centre/index.ts

@@ -336,6 +336,15 @@ export class Helpers {
         return expect(this.page.locator(".mx_ThreadPanel")).toBeVisible();
     }
 
+    /**
+     * Assert that the thread panel is focused (actually the 'close' button, specifically)
+     */
+    assertThreadPanelFocused() {
+        return expect(
+            this.page.locator(".mx_ThreadPanel").locator(".mx_BaseCard_header").getByTitle("Close"),
+        ).toBeFocused();
+    }
+
     /**
      * Populate the rooms with messages and threads
      * @param room1