fix(fedramp): remove generated files and add security-checks action

[cx-rui-araujo]

Propose changes:

• Remove 'cdk.out' folder because it was added in development by mistake. This is generated when running aws-cdk (https://www.npmjs.com/package/aws-cdk).
• Remove 'package-lock.json' because 'projen' is using yarn to install dependencies, so their update history is inside 'yarn.lock'.
• Add 'security-check' action to run trivy and grype.