Setup SecretsManager for JWT secret, DB login crews, etc.

[briri]

We need to setup AWS SecretsManager to store things like:

• shared JWT Secret
• RDS DB user credentials

The Secrets should get rotated on a regular basis and ECS should be setup to work with the rotation. For example, when it comes time to rotate, leave the old and new in place until ECS has finished cycling out the containers that still reference the old secrets