CLI feats for juturna hub

[b3by]

Description

This PR introduces the hub command for the juturna API. Through it, it is possible to:

• log into the juturna plugin registry, and fetch authorisation tokens
• search for plugins
• download plugins
• publish plugins

PR type
Select all the labels that apply to this PR.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Code refactoring
• Performance improvement
• Test update
• Build/CI configuration change
• Other (please describe):

Key modifications and changes

New command available in the CLI.

Additional context

Testing is possible by setting the proper endpoint as environment variable. The first step is to login.

$ JUTURNA_HUB_URL=<hub_address> python -m juturna hub login -e your_email@mail.com -p your_password

This will fetch an auth token, and store it in ~/.cache/juturna/credentials, alongside the requesting user id.

After that, it is possible to perform all the hub operations.

$ JUTURNA_HUB_URL=<hub_address> python -m juturna hub search node_name
$ JUTURNA_HUB_URL=<hub_address> python -m juturna hub get node_name
$ JUTURNA_HUB_URL=<hub_address> python -m juturna hub publish node_dir --name ...