The `client_secret_post` authentication method will be used when the discovery document defines `token_endpoint_auth_methods_supported`, includes `client_secret_post`, and does not include the default `client_secret_basic`.
A new (optional) site setting is introduced which allows `claims` to be explicitly requested.
Co-authored-by: David Taylor <david@taylorhq.com>
Previously an error loading the discovery document would raise an exception. Now, it will display an error to the user, and log the error for site admins to view at `/logs`. Specs are updated and improved accordingly.
This moves the discovery document fetching out of OmniAuth and into Discourse. This makes it available for the upcoming rp-initiated-logout support.