setup cd for backend web server-IN PROGRESS

[lourw]

👷 Changes

A brief summary of what changes were introduced. Screenshots are very much appreciated for frontend changes.

• added Dockerfile to containerize backend application
• split CI pipelines so that they only trigger when files in frontend/backend change
• added CI pipeline on build to generate image and push to AWS ECR
• added CD pipeline to update live application when code merges

Closes #15

🔦 Testing Instructions

✅ Checklist

• I have pulled the most recent changes from the main branch into my feature branch
• My code runs locally after pulling from main
• I have tested any new functionality locally (either manually or with unit tests)
• I have commented parts of my code that may be difficult to understand