xfs_quota: certain commands must always be available

xfs_quota: certain commands must always be available

Add CMD_ALL_FSTYPES to enable basic xfs_quota commands (e.g. help,
quit) to be run regardless of the filesystem type we are operating
on.

Use CMD_FLAG_FOREIGN_OK on commands suitable for foreign filesystems.
Refactor init_check_command in quota/init.c for clarity.

[ dchinner: CMD_SKIP_CHECK -> CMD_ALL_FSTYPES ]

Signed-off-by: Bill O'Donnell <billodo@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>