[ADVAPI32] Implement security descriptor management in CreateProcessAsUserCommon internal function

Currently CreateProcessAsUserCommon doesn't set a default descriptor for the newly duplicated token object for the new process nor it sets any security information for both the process and thread. This is wrong, because when the process is created on behalf of the user's security context,
it still uses the previous security information of the creator that initially gave birth to the process. CreateDefaultProcessSecurityCommon function will serve as a placeholder until CreatePrivateObjectSecurity is implemented.

Author: GeoB99