wic: Introduce --fsuuid and have --use-uuid make use of UUID too
First, allow for wic to be given a filesystem UUID to be used when
creating a filesystem. When not provided, wic will generate the UUID to
be used. Next, when --use-uuid is passed, we update the fstab to mount
things via UUID (and if not found, then use PARTUUID) as UUID is more
portable.
Signed-off-by: Tom Rini <trini@konsulko.com> Signed-off-by: Ross Burton <ross.burton@intel.com>
