[Message Actions] Report messages (#642)

* Add report messages feature

* Try to improve how snackbars are delivered

---------

Co-authored-by: ElementBot <benoitm+elementbot@element.io>

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/room/MatrixRoom.kt

@@ -112,4 +112,6 @@ interface MatrixRoom : Closeable {
     suspend fun setName(name: String): Result<Unit>
 
     suspend fun setTopic(topic: String): Result<Unit>
+
+    suspend fun reportContent(eventId: EventId, reason: String, blockUserId: UserId?): Result<Unit>
 }