The button state now indicates if the next video will be started in
fullscreen, or there is already one video in fullscreen.

This removes unused pointering. Furthermore, for nonembedded windows
the video size is set directly to avoid strange resizing after window
creation.

Now, everything from the video menu and the basic stuff like fullscreen
should work. If it does'nt (e.g. fullscreen and resize with video-splitter module enabled)
please blame the core first. ;-)

TODO: There might be some getVout()-calls left which should be investigated.

close #6814

Now, every video window is responsible for the fullscreen handling for its own.
Furthermore, fullscreen now acts entirely in response to vout events, and not over the
playlist fullscreen variable callback anymore.
Native fullscreen mode should also work correctly, but of course only
for embedded video in mainwindow.

This should fix resizing for all (one-)vout-window variants.
Furthermore, this fixes a small bug regarding aspect ratio enforcement.

Note that this commit will break some stuff for non-embedded cases, for now.

refs #6814

Now, we have two classes (instantiated from the xib file for each window)
with controls bar stuff:
- VLCControlsBarCommon holds all code common for main and detached window
- VLCMainWindowControlsBar adds code specific for the main window bar

With that, we can avoid all these redundant code for o_detached_*, furthermore
this decouples all detached window control bar stuff from MainWindow.m.

The objects can be accessed through the controlsBar method.

and move detached_titlebar_view stuff to detached window

moved custom zoom/minimize/close implementation, added new file for window related stuff
fixed minimize / close support for !video-deco window