on_after_login hook (#1092)

* on_after_login minimal impl.

Questions: is the spot logical for after method? Is after the internal login call.
Would before_login be needed? Maybe not, as auth is the way to do pre-login things.

Added fastapi request as a param just in case, as other callbacks had it too.

Docs addition is missing.

* tried to complete the implementation, but the test with user_manager.on_after_login.called fails though

* move on_after_login tests to right place, to TestLogin. These ones pass.

TODO: check TestCallback

* on_after_login tests to TestCallback too, for oauth. Apparently test_redirect_url_router fires the callback too, I guess that's correct, am not using oauth myself.

* fix formatting with make format

* docs for on_after_login

Co-authored-by: Toni Alatalo <toni.alatalo@gmail.com>

fastapi_users/router/auth.py

@@ -1,6 +1,6 @@
 from typing import Tuple
 
-from fastapi import APIRouter, Depends, HTTPException, Response, status
+from fastapi import APIRouter, Depends, HTTPException, Request, Response, status
 from fastapi.security import OAuth2PasswordRequestForm
 
 from fastapi_users import models
@@ -49,6 +49,7 @@ def get_auth_router(
         responses=login_responses,
     )
     async def login(
+        request: Request,
         response: Response,
         credentials: OAuth2PasswordRequestForm = Depends(),
         user_manager: BaseUserManager[models.UP, models.ID] = Depends(get_user_manager),
@@ -66,7 +67,9 @@ def get_auth_router(
                 status_code=status.HTTP_400_BAD_REQUEST,
                 detail=ErrorCode.LOGIN_USER_NOT_VERIFIED,
             )
-        return await backend.login(strategy, user, response)
+        login_return = await backend.login(strategy, user, response)
+        await user_manager.on_after_login(user, request)
+        return login_return
 
     logout_responses: OpenAPIResponseType = {
         **{