Revamp authentication (#831)

* Implement Transport classes

* Implement authentication strategy classes

* Revamp authentication with Transport and Strategy

* Revamp strategy and OAuth so that they can use a callable dependency

* Update docstring

* Make ErrorCode a proper Enum and cleanup unused OpenAPI utils

* Remove useless check

* Tweak typing in authenticator

* Update docs

* Improve logout/destroy token logic

* Update docs

* Update docs

* Update docs and full examples

* Apply formatting to examples

* Update OAuth doc and examples

* Add migration doc

* Implement Redis session token

* Add Redis Session documentation

* RedisSession -> Redis

* Fix links in docs

examples/mongodb/sqlalchemy/app/app.py

@@ -0,0 +1,38 @@
+from fastapi import Depends, FastAPI
+
+from app.db import database
+from app.models import UserDB
+from app.users import auth_backend, current_active_user, fastapi_users
+
+app = FastAPI()
+
+app.include_router(
+    fastapi_users.get_auth_router(auth_backend), prefix="/auth/jwt", tags=["auth"]
+)
+app.include_router(fastapi_users.get_register_router(), prefix="/auth", tags=["auth"])
+app.include_router(
+    fastapi_users.get_reset_password_router(),
+    prefix="/auth",
+    tags=["auth"],
+)
+app.include_router(
+    fastapi_users.get_verify_router(),
+    prefix="/auth",
+    tags=["auth"],
+)
+app.include_router(fastapi_users.get_users_router(), prefix="/users", tags=["users"])
+
+
+@app.get("/authenticated-route")
+async def authenticated_route(user: UserDB = Depends(current_active_user)):
+    return {"message": f"Hello {user.email}!"}
+
+
+@app.on_event("startup")
+async def startup():
+    await database.connect()
+
+
+@app.on_event("shutdown")
+async def shutdown():
+    await database.disconnect()