AAI-204 Automatically build Docker image and push to AWS ECR via GitHub Actions

[marius-mather]

Description

AAI-204: build the app as a Docker image and push it to AWS ECR so we can easily deploy it

Changes

• Dockerfile to build the Docker image
• GitHub Action to push to AWS when we commit to main

Checklist

• I have commented my code, particularly in hard-to-understand areas
• I have added unit / integration tests that prove my fix is effective or that my feature works
• I have run all tests locally and they pass
• I have updated the documentation (if applicable)