extra_mounts: Support docker --mount parameter in addition to current --volume

[an-dr-eas-k]

What would you like to be added:
currently the configuration for the extra_mounts config structure is translated in the docker argument --volume with syntax --volume=host_path:container_path. I followed the guide here https://kind.sigs.k8s.io/docs/user/local-registry/ and wanted to terraform the process. I am now stuck at the point to dynamically mount my local config dir to the container directory with name /etc/containerd/certs.d/localhost:5001/. The colon in the directory name cannot be mapped with the --volume argument.

I suggest an additional extra_mounts structure that is translated to the --mount parameter of docker.

Why is this needed:
Doing so would allow colons in directory names.

[BenTheElder]

xref: #1966

This is probably happening in some future API revision, subject to bandwidth.

FWIW I recommend mounting the whole [..]certs.d/

[an-dr-eas-k]

thanks, that helps!