We've decided to add a 'brand' field to help clients decide how to style the
buttons.
Also, fix up the allowed characters for idp_id, while I'm in the area.
* Implement CasHandler.handle_redirect_request
... to make it match OidcHandler and SamlHandler
* Clean up interface for OidcHandler.handle_redirect_request
Make it accept `client_redirect_url=None`.
* Clean up interface for `SamlHandler.handle_redirect_request`
... bring it into line with CAS and OIDC by making it take a Request parameter,
move the magic for `client_redirect_url` for UIA into the handler, and fix the
return type to be a `str` rather than a `bytes`.
* Define a common protocol for SSO auth provider impls
* Give SsoIdentityProvider an ID and register them
* Combine the SSO Redirect servlets
Now that the SsoHandler knows about the identity providers, we can combine the
various *RedirectServlets into a single implementation which delegates to the
right IdP.
* changelog
The CI appears to use the latest version of isort, which is a problem when isort gets a major version bump. Rather than try to pin the version, I've done the necessary to make isort5 happy with synapse.
By persisting the user interactive authentication sessions to the database, this fixes
situations where a user hits different works throughout their auth session and also
allows sessions to persist through restarts of Synapse.
