Prepare new Dockerfile for K8s Compatibility

[ryan-mcneil]

Description

• This PR introduces what will some day replace the current Dockerfile and associated files.
• The new Dockerfile is based on the template/boilerplate Dockerfile provided with new Rails apps (specifically 7.1.3)

This Dockerfile/Docker Compose file are development ready. To run locally, you can specify the "new" dockerfile:
docker compose -f docker-compose-new.yml up, and append the flag --build to the end of the command to pick up any changes to the image.

Original issue(s)

department-of-veterans-affairs/va.gov-team#79340

Testing done

• Image successfully builds and listens on localhost:3000
• Specs can be run in container

Screenshots

Acceptance criteria

• [ ]

Definition of done

• Events are logged appropriately
• Documentation has been updated, if applicable
• A link has been provided to the originating GitHub issue (or connected to it via ZenHub)
• No sensitive information (i.e. PII/credentials/internal URLs/etc.) is captured in logging, hardcoded, or specs