Add detection for sensitive config values in Compose files

[commit111]

Description

Detects potentially sensitive environment variables in Compose files, and gives a warning for the user to use defang config set ENV_VAR to securely store those values.

It uses various detectors from https://github.com/DefangLabs/secret-detector to detect secrets, including: aws_client_id, github, high_entropy_string, keyword, url_password.

Linked Issues

Fixes #938

Checklist

• I have performed a self-review of my code
• I have added appropriate tests
• I have updated the Defang CLI docs and/or README to reflect my changes, if necessary

[jordanstephens]

If you can, maybe add some comments to the jsonCfg, so that we can easily understand how the config values relate to the problem we are solving.

Good job on this!

[lionello]

nits