v2 beta: semi-closed launch

[josh-chamberlain]

Context

Part of #248 Follows #540

Requirements

• [ ] execute order #456, leaving Airtable in the dust
• [ ] change the new source and new request to use the v2 forms
• [ ] start using retool for intake
• [ ] check to make sure everything is working
  • [ ] make sure the github integration works
  • [ ] make sure the retool integration works
  • [ ] make sure notifications work
• [ ] activate requests <> github integration: #299
• [ ] show follow and make a request buttons only to signed in users
• [ ] add requests to the app/search results for only already-signed-in users
• [ ] make the v2 fork the main fork; somehow preserve v1 code, just in case
• [ ] turn on notifications for followed searches
• [ ] add a note to sign up: "We're currently in closed beta. Reach out to contact@pdap.io if you would like access."

Non-code

• [ ] share sign up with a portion of our network, and set up feedback sessions

Docs

• Docs for users explaining how sign up, sign in, following/notifications, and requests work