RoomList: Change room on drag enter

With a delay. Allows to drag a file to NeoChat and switch rooms.

In the future we might want to allow dropping a file onto a
room to send it.

src/rooms/RoomListPage.qml

@@ -163,6 +163,7 @@ Kirigami.Page {
                             connection: root.connection
                             collapsed: root.collapsed
                             highlighted: RoomManager.currentRoom === currentRoom
+                            openOnDrag: true
                         }
                     }