Win32 UI: Some cleanups and simplifications, fix some small bugs.

This does the following:
* Simplifies the menu translation code: it doesn't need to dictate if menu options are enabled or not, nor if items are checked. The menu bar automatically does these afterward anyway. I'd like to see if this can be even further simplified in the future, but that will be in a separate pullrq.
* Removes WM_USER_ATRAC_STATUS_CHANGED since it no longer has a menu item to change.
* Moves globalUIState editing to NewUI where it belongs(previously WndMainWindow was changing it, which is sort of a silly place to do it) when entering More Settings/Control Mapping.
* Remove dead code relating to multiple removed menu options.
* Fixes #3282.
* Fixes "Keep PPSSPP on Top" when coming out of fullscreen. Previously if you exited fullscreen with the option ON, it wouldn't be always on top anymore.
* Fixes #3352.