Add jest and codegen config docs

[dac09]

Related to https://github.com/redwoodjs/redwood/pull/4096

• Moves babel doc into a unified "Project Configuration" section
• Adds docs for jest config
• Adds docs for graphql codegen config

[callingmedic911]

Closes https://github.com/redwoodjs/redwoodjs.com/issues/948. 😬

[thedavidprice]

FYI @jtoar If there are any updates to page or section links, we'll need to update in CLI as well:

• See this commit for reference: https://github.com/redwoodjs/redwood/pull/4096/commits/af48e1ddcaf728c71d955df08671e2d78ad2da1e