mdssvc: avoid direct filesystem access, use the VFS

mdssvc: avoid direct filesystem access, use the VFS

This ensures mdssvc uses the same FileIDs as the fileserver as well as Spotlight
can be used working on a virtual filesystem like GlusterFS.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14740
RN: Spotlight RPC service doesn't work with vfs_glusterfs

Signed-off-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Autobuild-User(master): Ralph Böhme <slow@samba.org>
Autobuild-Date(master): Wed Jun 16 05:59:13 UTC 2021 on sn-devel-184

(backported from commit 620b99144359f45aa69c13731db8d793cfbba197)
[slow@samba.org: smbd_check_access_rights_fsp() doesn't take dirfsp arg]