Add configuration option for enabling/disabling the asynchronous window
handling. The feature might cause unforeseen issues, so by default it is
off. It can be enabled with setting the option async_window_handling to
true.
Unresponsive windows might cause Komorebi to hang because functions like
SetWindowPos wait for the target window's WindowProc.
I changed most SetWindowPos calls to use the SWP_ASYNCWINDOWPOS flag,
which should avoid hanging, and I changed the one
WindowsApi::move_window call to use position_window instead. I also
changed the ShowWindow to ShowWindowAsync.
The only issue I noticed was that it caused the stackbar to disappear
(and/or flicker), probably because the window is modified right after
moving it, so I disabled the async position_window for that.
Kuukunen