Add fetchMembers and use it when init timeline (import again rust-sdk with fix on poisoning)

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

@@ -41,6 +41,10 @@ class FakeMatrixRoom(
         return FakeMatrixTimeline()
     }
 
+    override suspend fun fetchMembers(): Result<Unit> {
+        return Result.success(Unit)
+    }
+
     override suspend fun userDisplayName(userId: String): Result<String?> {
         return Result.success("")
     }