Support X11 selection mechanism for messages

TODO.md

@@ -25,8 +25,6 @@
   - GIF glitchy border
   - Combined pure media events time looks bad
 
-  - Copy to X11 selection with new CppUtils class
-
 - RoomMessageNotice
 
 - Refactoring

src/qml/Base/HSelectableLabelContainer.qml

@@ -39,6 +39,8 @@ FocusScope {
     }
 
 
+    onJoinedSelectionChanged: Clipboard.selection = joinedSelection
+
     onDragStarted: {
         draggedItem.Drag.active = true
     }