Credential providers and NT6.x like LogonUI

In NT 5.x, winlogon loads a GINA dll that handles the graphical UI and authentication. In XP, logonui.exe is called by MSGINA. In NT 6.x, GINA was removed and replaced with credential providers, which display their UI inside logonui.exe (which is launched directly from winlogon). As we move towards supporting third party credential providers, create a GINA shim to load an NT 6.x like logonUI that can host credential providers. Also, use view DLLs for logonui themes with a CLI fallback for stripped builds (similar to Windows Server Core).