Subdirectory Package Support

[israelias]

Make it easy to clone frontend without backend and vice versa.

Yarn workspaces is the obvious way to go but a package.json in a Python/Flask backend subdirectory would be relatively useless...

• Add root package.json
• Add backend package.json
• Modify frontend package.json name to work with yarn workspaces from root directory
• Add start scripts in root package.json to run development frontend, backend, and both concurrently.
• Add scripts to backend/package.json that run the various subdirectory python commands for development and production
• Add build scripts in root package.json to run build commands of respective subdirectories
• Add test scripts in root package.json to run test commands of respective subdirectories