Add build/remove image commands to container

[gerrod3]

Summary

You can build an image in a container repository using a container file and list of artifacts. For push repositories you can remove an image by providing its digest. The build command could benefit from the CLI being able to navigate a directory and upload the necessary artifacts for the command.

Examples

pulp container repository build --repository foo --container-file "filename_or_href" --artifacts "directory_or_json"
pulp container repository -t push remove --repository phoo --digest "manifest_digest" maybe this is named bad?

[ipanova]

how about pulp container repository build-image