* Move users router in sub-module
* Factorize UserRouter into EventHandlersRouter
* Implement OAuth registration/login router
* Apply isort/black
* Remove temporary pytest marker
* Fix httpx-oauth version in lock file
* Ensure ON_AFTER_REGISTER event is triggered on OAuth registration
* Add API on FastAPIUsers to generate an OAuth router
* Improve test coverage of FastAPIUsers
* Small fixes
* Write the OAuth documentation
* Fix SQL unit-tests by avoiding collisions in SQLite db files
