Threads - first iteration (#5165)

* Initial threads support: parse `ThreadSummary`.

Replace several `isThreaded` values with `EventThreadInfo`, which contains the info about the event either being the root of a thread or part of it.

* Add `Threaded` timeline mode

* Add a `liveTimeline` parameter to `TimelineController`'s  constructor. This way we can customise which timeline will be used as the 'live' one. Also add `@LiveTimeline` DI qualifier for the actual live timeline of the room.

* Create `ThreadedMessagesNode`. Allow opening a thread in a separate screen.

* Add the callbacks for the list menu actions - even if they're the wrong ones and will send the data to the room instead

* Send attachments and location in threads

* Fix polls in threads, add support for sending voice messages in threads

* Display thread summaries only when the feature flag is enabled

* Use 'Reply' instead of 'Reply in thread' when in threaded timeline mode

* Remove incorrect usage of `Timeline` in `MessageComposerPresenter`. This led to replies to threaded events not appearing as actual replies.

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Co-authored-by: ElementBot <android@element.io>

libraries/featureflag/api/src/main/kotlin/io/element/android/libraries/featureflag/api/FeatureFlags.kt

@@ -93,4 +93,11 @@ enum class FeatureFlags(
         // False so it's displayed in the developer options screen
         isFinished = false,
     ),
+    HideThreadedEvents(
+        key = "feature.thread_timeline",
+        title = "Threads",
+        description = "Renders thread messages as a dedicated timeline. Restarting the app is required for this setting to fully take effect.",
+        defaultValue = { false },
+        isFinished = false,
+    )
 }