Enhance mount parameter

[JensHeinrich]

/kind feature

Description

Use same structure as docker_container for mounts

Additional information you deem important (e.g. issue happens only occasionally):

This should be done now, so users can switch from docker_container to podman_container with ease (#99 )

Changes

• Replace mount parameter with mounts (or keep it for backwards compability)
• Parse mounts as a list of dictionaries

[jtryggveson]

I would also appreciate support for multiple mounts, either plain list or list of dicts.