OAuth User disable auto create and require approval

### Problem Statement

Specially in Google OAuth...

### Solution Brainstorm

Adding an option to make users to request to join instead creating users

### Product Area

Sign In

The issue names no files, tests, or entry points. Start by locating the Google OAuth sign-in flow and the code that creates users, then clarify how approval requests should be represented and reviewed. Done means users can be prevented from being auto-created and can request access for approval.

Written by the indexing model from the issue text.