Initialize app + Transfer code

[machikoyasuda]

closes #1
closes #3

What this PR does

• Transfers required localhost/server files from Benefits app
• Creates 2 Dockerfiles: One for production (Dockerfile - runs a non-root user, no dev tooling, runs flask app), one for development (Dockerfile.dev - runs production with a root user, installs dev tooling and python tooling)
• Creates docker-compose.yml for development that defines 2 services: server for production and dev for development. dev runs Dockerfile.dev with FLASK environment variables, debugger port defined and runs app.py directly
• Defines .devcontainer file for development that starts the dev service from docker-compose.yml

How to run this PR

Initial build

• docker-compose build server

Launch in DevContainer + Debug mode

• Launch in Container on VS Code
• (May have to restart for extensions to work)
• Run in Debug mode
• Add breakpoint
• open localhost:5000
• server check: curl http://localhost:5000/ -iv

[machikoyasuda]

2 issues so far with this setup:

1. No Git
2. No permissions to save files!

[thekaveman]

Looking great so far! I was able to get the devcontainer running locally and hit a breakpoint with debug mode active.

I made a few suggestions, nothing major. There was one minor fix to the docs.