Loading threads with server-side assistance (#9356)

* Fix bug with message context menu
* fix bug where ThreadSummary failed if no last reply is available
* Fix relations direction API
* Use same API for threads as for any other timeline
* Determine if event belongs to thread on jumping to event
* properly listen to thread deletion
* Add thread redaction tests
* Add fetchInitialEvent tests
* Paginate using default TimelinePanel behaviour
* Remove unused threads deleted code

Co-authored-by: Germain <germain@souquet.com>
Co-authored-by: Germain <germains@element.io>

test/test-utils/test-utils.ts

@@ -212,6 +212,7 @@ type MakeEventPassThruProps = {
 };
 type MakeEventProps = MakeEventPassThruProps & {
     type: string;
+    redacts?: string;
     content: IContent;
     room?: Room["roomId"]; // to-device messages are roomless
     // eslint-disable-next-line camelcase
@@ -245,6 +246,7 @@ export function mkEvent(opts: MakeEventProps): MatrixEvent {
         event_id: "$" + Math.random() + "-" + Math.random(),
         origin_server_ts: opts.ts ?? 0,
         unsigned: opts.unsigned,
+        redacts: opts.redacts,
     };
     if (opts.skey !== undefined) {
         event.state_key = opts.skey;