Support JSON for --object in all tools and in HMP object_add in the same
way as it is supported in qobject_input_visitor_new_str().

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20210312131921.421023-1-kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>