Create NeochatRoomMember as a shim for RoomMember

The intention is that NeochatRoomMember can be created passed to QML and then be fully managed by it. It effectively just grabs the current RoomMember, calls the correct function then discards it so that we don't end up trying to access an already deleted state event.

src/timeline/MessageDelegate.qml

@@ -50,7 +50,7 @@ TimelineDelegate {
      *
      * @sa Quotient::RoomMember
      */
-    required property var author
+    required property NeochatRoomMember author
 
     /**
      * @brief The model to visualise the content of the message.
@@ -365,7 +365,7 @@ TimelineDelegate {
         property bool showUserMessageOnRight: NeoChatConfig.showLocalMessagesOnRight && root.author.isLocalMember && !NeoChatConfig.compactLayout && !root.alwaysFillWidth
 
         function showMessageMenu() {
-            RoomManager.viewEventMenu(root.eventId, root.room, root.selectedText);
+            RoomManager.viewEventMenu(root.eventId, root.room, root.author, root.selectedText);
         }
     }
 }