set user permissions on image if run with sudo or in docker
run/vbox & run/hetzner: run qemu-img in docker if not available in path
Signed-off-by: Adphi <philippe.adrien.nousse@gmail.com>
refactor: use Option func pattern
fix: build respect the --force flag
fix: compute correct in-docker input and outpout mount paths
Signed-off-by: Adphi <philippe.adrien.nousse@gmail.com>