CORE-11933 and PR #621.
Since this API is also called from WINSRV when calling the AllocConsole() API,
it can be tested more-or-less easily. The internal helper IntResolveDesktop()
is also tested during process connection to a window station, when such process
first calls a USER32 or GDI32 function.
This is also the functionality tested by the user32:desktop apitest.
- Adjust how IntResolveDesktop() is called.
Also, improve NtUserSetWindowStationUser() capture order, make psid optional as it should (and avoid a user-mode triggered BSOD), and initialize luidUser only when everything succeeded.
