Fix threads fallback incorrectly targets root event (#9229)

* Use RelationType enum instead of hardcoded value

* Fix threads replies fallback to target last reply

* Only unsubscribe from threads events if needed

* fix strict null check

* fix strict null checks

* strict null checks

* fix typing

* Unsubscribe listeners if new thread is `null`

Co-authored-by: Faye Duxovni <fayed@element.io>

* Update strict null checks

* Type HTMLElement as nullable

* Add thread fallback integration test

* lint fix

* Update snapshots

* Add test after changing thread

* Remove test comment

* update snapshot

* fix room context test utility

* Add ThreadListContextMenu test

* lint fix

* fix thread rendering

Co-authored-by: Faye Duxovni <fayed@element.io>
Co-authored-by: Michael Telatynski <7t3chguy@gmail.com>

test/voice-broadcast/components/molecules/__snapshots__/VoiceBroadcastPlaybackBody-test.tsx.snap

@@ -195,6 +195,7 @@ exports[`VoiceBroadcastPlaybackBody when rendering a buffering voice broadcast s
         <div
           aria-label="Loading..."
           class="mx_Spinner_icon"
+          data-testid="spinner"
           role="progressbar"
           style="width: 32px; height: 32px;"
         />