Return cached room members before fetching new ones, do it in batches (#2274)

* Use cached users from the Rust SDK.

Also lazy load received users by batches.

* Create `RoomMemberListFetcher` to wrap all the room member loading logic

* Ensure we clear `RoomMember` Rust references if the fetching coroutine is canceled

libraries/matrix/test/src/main/kotlin/io/element/android/libraries/matrix/test/room/FakeMatrixRoom.kt

@@ -171,9 +171,7 @@ class FakeMatrixRoom(
     override val roomNotificationSettingsStateFlow: MutableStateFlow<MatrixRoomNotificationSettingsState> =
         MutableStateFlow(MatrixRoomNotificationSettingsState.Unknown)
 
-    override suspend fun updateMembers(): Result<Unit> = simulateLongTask {
-        updateMembersResult
-    }
+    override suspend fun updateMembers() = Unit
 
     override suspend fun updateRoomNotificationSettings(): Result<Unit> = simulateLongTask {
         val notificationSettings = notificationSettingsService.getRoomNotificationSettings(roomId, isEncrypted, isOneToOne).getOrThrow()