smbd: Move fcb_or_dos_open() out of open_file_ntcreate()

smbd: Move fcb_or_dos_open() out of open_file_ntcreate()

This is SMB1-only and pre-ntcreate with only 3 callers that look at
NTCREATEX_OPTIONS_PRIVATE_DENY_[DOS|FCB]. It is a bit less efficient
if it kicks in (we have to recreate the fsp), but SMB1 is less and
less popular, and this particular share mode combination from the
open&x family of calls might not be worth optimizing for.

This adds smb1_utils.[ch] as a kitchen sink for functions that can go
away once we drop SMB1.

Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Stefan Metzmacher <metze@samba.org>