qt: playlist: VLC 4: Double-clicking window titlebar regardless of speed maximizes it

Fixes #26276 (closed)

The CSDTitlebarTapnDragHandler snippet was using the onTapped signal without any set delay between the clicks which was causing the windows to maximize even when the second click was long after the first one. 

Fixed this issue by replacing that signal with onDoubleTapped in which the signal is emitted only when the parent item is tapped twice between a short span of time.

The window is now maximizing/minimizing only on proper double taps as tested on my local computer.