This function is a condensed version of LpkPSMTextOut() (from lpk.dll),
but not bug-for-bug equivalent.
The main difference is that the underscore is drawn without taking into
account any kind of script processing.
Added callback function that redirects calls to GreExtTextOutW that didn't went through lpk BiDi processing, calls that are from the kernel.
Completely solves JIRA issue CORE-6910.
Observed via API monitoring.
This corresponds to the case where Win32k creates a window station whose name is based on the logon session identifier for the calling process.
Add also a note about the fact that we need to use a per-session-based WindowStation directory name, as done already in Win32k.
CORE-11933 and PR #621.
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.
