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

docs/configuration/authentication/transports/bearer.md

@@ -0,0 +1,41 @@
+# Bearer
+
+With this transport, the token is expected inside the `Authorization` header of the HTTP request with the `Bearer` scheme. It's particularly suited for pure API interaction or mobile apps.
+
+## Configuration
+
+```py
+from fastapi_users.authentication import BearerTransport
+
+bearer_transport = BearerTransport(tokenUrl="auth/jwt/login")
+```
+
+As you can see, instantiation is quite simple. It accepts the following arguments:
+
+* `tokenUrl` (`str`): The exact path of your login endpoint. It'll allow the interactive documentation to automatically discover it and get a working *Authorize* button. In most cases, you'll probably need a **relative** path, not absolute. You can read more details about this in the [FastAPI documentation](https://fastapi.tiangolo.com/tutorial/security/first-steps/#fastapis-oauth2passwordbearer).
+
+## Login
+
+This method will return the in the following form upon successful login:
+
+!!! success "`200 OK`"
+    ```json
+    {
+        "access_token": "eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJ1c2VyX2lkIjoiOTIyMWZmYzktNjQwZi00MzcyLTg2ZDMtY2U2NDJjYmE1NjAzIiwiYXVkIjoiZmFzdGFwaS11c2VyczphdXRoIiwiZXhwIjoxNTcxNTA0MTkzfQ.M10bjOe45I5Ncu_uXvOmVV8QxnL-nZfcH96U90JaocI",
+        "token_type": "bearer"
+    }
+    ```
+
+> Check documentation about [login route](../../../usage/routes.md#post-login).
+
+## Logout
+
+The logout method with this transport returns nothing.
+
+## Authentication
+
+This method expects that you provide a `Bearer` authentication with a valid token corresponding to your strategy.
+
+```bash
+curl http://localhost:9000/protected-route -H'Authorization: Bearer eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJ1c2VyX2lkIjoiOTIyMWZmYzktNjQwZi00MzcyLTg2ZDMtY2U2NDJjYmE1NjAzIiwiYXVkIjoiZmFzdGFwaS11c2VyczphdXRoIiwiZXhwIjoxNTcxNTA0MTkzfQ.M10bjOe45I5Ncu_uXvOmVV8QxnL-nZfcH96U90JaocI'
+```

docs/configuration/authentication/transports/cookie.md

@@ -0,0 +1,41 @@
+# Cookie
+
+Cookies are an easy way to store stateful information into the user browser. Thus, it is more useful for browser-based navigation (e.g. a front-end app making API requests) rather than pure API interaction.
+
+## Configuration
+
+```py
+from fastapi_users.authentication import CookieTransport
+
+cookie_transport = CookieTransport(cookie_max_age=3600)
+```
+
+As you can see, instantiation is quite simple. It accepts the following arguments:
+
+* `cookie_name` (`fastapiusersauth`): Name of the cookie.
+* `cookie_max_age` (`Optional[int]`): The lifetime of the cookie in seconds. `None` by default, which means it's a session cookie.
+* `cookie_path` (`/`): Cookie path.
+* `cookie_domain` (`None`): Cookie domain.
+* `cookie_secure` (`True`): Whether to only send the cookie to the server via SSL request.
+* `cookie_httponly` (`True`): Whether to prevent access to the cookie via JavaScript.
+* `cookie_samesite` (`lax`): A string that specifies the samesite strategy for the cookie. Valid values are `lax`, `strict` and `none`. Defaults to `lax`.
+
+## Login
+
+This method will return a response with a valid `set-cookie` header upon successful login:
+
+!!! success "`200 OK`"
+
+> Check documentation about [login route](../../../usage/routes.md#post-login).
+
+## Logout
+
+This method will remove the authentication cookie:
+
+!!! success "`200 OK`"
+
+> Check documentation about [logout route](../../../usage/routes.md#post-logout).
+
+## Authentication
+
+This method expects that you provide a valid cookie in the headers.