zenodo-validate CLI and GitHub action

Describe the feature you would like to see in eossr

• zenodo-validate CLI
• zenodo-validate GitHub action

Being able to validate a .zenodo.json file with a CLI.

In what context do you need this feature?

After creating a .zenodo.json files (with the codemeta2zenodo converter or not), people need to make sure their file is valid before making a release. The eossr-check-zenodo-connection includes such a feature, I'd like to have it as a separate one.

A lot of people seem to request this from zenodo (since 2018!): https://github.com/zenodo/zenodo/issues/1606

Expected behavior?

• pass a .zenodo.json file, it connects to the sandbox, make a fake deposit, deletes it.

Possible way(s) to implement

• CLI: already implemented, just some refactoring
• GitHub action

See #21