Don't allow long-pressing on non-touchscreen devices

It isn't the right kind of interaction on a computer with a mouse or
trackpad, it should be relegated to touchscreen only. This should
hopefully cover everything from room list delegates to messages.

src/qml/RoomDelegate.qml

@@ -42,8 +42,6 @@ Delegates.RoundedItemDelegate {
         }
     }
 
-    onPressAndHold: createRoomListContextMenu()
-
     Keys.onSpacePressed: clicked()
     Keys.onEnterPressed: clicked()
     Keys.onReturnPressed: clicked()
@@ -54,6 +52,11 @@ Delegates.RoundedItemDelegate {
         onTapped: (eventPoint, button) => root.createRoomListContextMenu()
     }
 
+    TapHandler {
+        acceptedDevices: PointerDevice.TouchScreen
+        onLongPressed: root.createRoomListContextMenu()
+    }
+
     contentItem: RowLayout {
         spacing: Kirigami.Units.largeSpacing