Display poll notifications in the notification drawer (#1467)

Display notifications for polls as if they were message events.

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/notification/NotificationData.kt

@@ -61,7 +61,10 @@ sealed interface NotificationContent {
         ) : MessageLike
         data object RoomRedaction : MessageLike
         data object Sticker : MessageLike
-        data class Poll(val question: String) : MessageLike
+        data class Poll(
+            val senderId: UserId,
+            val question: String,
+        ) : MessageLike
     }
 
     sealed interface StateEvent : NotificationContent {