feat: Use SOPS to encrypt secrets

[sunib]

• Adding sops support so that we encrypt secrets
• The config setup is a bit rough: I would like to support a sops config per repo at least.
• Think about caching and how to handle that the right way.

[gitguardian]

️✅ There are no secrets present in this pull request anymore.

If these secrets were true positive and are still valid, we highly recommend you to revoke them.
While these secrets were previously flagged, we no longer have a reference to the
specific commits where they were detected. Once a secret has been leaked into a git
repository, you should consider it compromised, even if it was deleted immediately.
Find here more information about risks.

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