build: Add out-of-tree support

Signed-off-by: Fabian Deutsch <fabiand@fedoraproject.org>
imagbase: Add some more arguments

Signed-off-by: Fabian Deutsch <fabiand@fedoraproject.org>
hooks: Improve persistence hook

Signed-off-by: Fabian Deutsch <fabiand@fedoraproject.org>