feat: add secret management

[lucarin91]

Motivation

We need to store secrets and make them accessible to the containers.

Change description

The idea was to store each secret on a different file and then attach the file to the container with the docker secret management, i.e., https://docs.docker.com/compose/how-tos/use-secrets/.

Containers could access the secret by reading the file /run/secrets/<nome-secret>.

Secrets can be managed with the api:

• GET /v1/apps/{appID}/secrets
• PATCH /v1/apps/{appID}/bricks/{brickID}
• DELETE /v1/apps/{appID}/bricks/{brickID}

Additional Notes

Reviewer checklist

• PR addresses a single concern.
• PR title and description are properly filled.
• Changes will be merged in main.
• Changes are covered by tests.
• Logging is meaningful in case of troubleshooting.

[lucarin91]

• add tests