OIDC: Get accessToken and complete login

[kerryarchibald]

3.1.1. Authorization Code Flow Steps
The Authorization Code Flow goes through the following steps.

1. Client prepares an Authentication Request containing the desired request parameters.
2. Client sends the request to the Authorization Server.
3. Authorization Server Authenticates the End-User.
4. Authorization Server obtains End-User Consent/Authorization.
5. Authorization Server sends the End-User back to the Client with an Authorization Code.
6. Client requests a response using the Authorization Code at the Token Endpoint.
7. Client receives a response that contains an ID Token and Access Token in the response body.
8. Client validates the ID token and retrieves the End-User's Subject Identifier.

https://openid.net/specs/openid-connect-core-1_0.html#CodeFlowAuth

This task addresses steps 6-8

Resources

• Client implementation guide
• synapse-admin implementation
• hydrogen implementation

Not included:

• guest login
• redirection to fragment after login OIDC: handle redirection to fragment after login #25656
• token refresh

AC

• query params are removed from the url post login