Chore: devcontainer setup

[thekaveman]

Cleans up the devcontainer setup and normalizes with benefits:

• Initialize the database as part of devcontainer startup - closes Run setup.py on devcontainer attach #125
• Get all the settings and extensions we like using - closes Normalize devcontainer settings/extensions with benefits #121
• Moves the compose.yml file to the root, so docker compose commands can be run from there

⚠️ Devs should update their .env file

The file will need to move from inside the .devcontainer/ directory to the root of the repository

[angela-tran]

This is great work - the dev experience is more consistent now 💯

Tested locally by:

• running cp .devcontainer/.env .env
• rebuilding the server image with docker compose build server
• choosing Rebuild and Reopen in Container in VS Code

[thekaveman]

@machikoyasuda want to make sure you see this and can run the containers without any issue!

[machikoyasuda]

In this PR or in a subsequent PR, the docs need to be updated to remove cd .devcontainer and note that setup.py is happening at app start. Otherwise, works great: I was able to move my .env file, build a new container, Rebuild and Reopen in Container, run the app, healthcheck and run all tests.

[machikoyasuda]

Great!