* docker_image: add network parameter
Add a network parameter to the docker_image module to specify the
network to use for RUN commands.
Called it network instead of network_mode as the latter seems like a
legacy of when there were just a few default options to choose from,
while now the name of an arbitrary network can be specified.
Fixes#21433
* Format description
* Update docker_image option_minimal_versions
* Ensure network_mode param optional
9be3ebc596