Allow passing a socket of an externally launched virtiofsd
to the vhost-user-fs device.
<filesystem type='mount'>
<driver type='virtiofs' queue='1024'/>
<source socket='/tmp/sock/'/>
</filesystem>
https://bugzilla.redhat.com/show_bug.cgi?id=1855789
Signed-off-by: Ján Tomko <jtomko@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
