Move api gen to frontend2, add back old frontend prettier, bump CI node version

[x] Bump frontend2 CI node version to 18
[x] Move toplevel api generation files to frontend2"
[x] ensure linting still runs on old frontend
[x] regenerate the API because the backend in main was different from the backend in frontend2

This PR also documents the api generation process and adds a list of important scripts to the frontend2/README.md

battlecode / galaxy