Add Digital Ocean credentials helper

[lionello]

Description

• Add the Digital Ocean Credentials Helper to authn chain.

Submitter Checklist

These are the criteria that every PR should meet, please check them off as you review them:

• [ ] Includes unit tests
• [ ] Adds integration tests if needed.

See the contribution guide for more details.

Reviewer Notes

• [ ] The code flow looks good.
• [ ] Unit tests and or integration tests added.

Release Notes

Describe any changes here so maintainer can include it in the release notes, or delete this block.

- add the Digital Ocean credentials helper, using `DIGITALOCEAN_TOKEN` for creating container registry creds