Set an empty Wayland input region for windows that is marked as both WS_EX_TRANSPARENT and WS_EX_LAYERED in order to match the Windows behavior.
Setting an empty input region prevents the compositor from giving the pointer focus to the corresponding surface in the first place, and improves consistency between the Win32 mouse and Wayland pointer focus states.
Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=58650
-- v3: winewayland: Pass through mouse events for transparent, layered windows.