By defining the full name for the docker image we avoid the issue that
occurs when using `podman` (tested on Fedora 38) where podman will prompt the
user for what docker repository to pull the image from.
author ardevd <edvard.holst@gmail.com> 1676983861 +0100
committer ardevd <ardevd@users.noreply.github.com> 1677705118 +0100
Write to the specified file if the user specifies a chan_point for
backup and also specifies an output file to write the backup to.
Fixes#7436
ardevd