Co-authored-by: Benjamin Koch <bbbsnowball@gmail.com>
This adds configuration flags that will match a user to pre-existing users
when logging in via OpenID Connect. This is useful when switching to
an existing SSO system.
'client_auth_method' commented out value was erronously 'client_auth_basic',
when code and docstring says it should be 'client_secret_basic'.
Signed-off-by: Jason Robinson <jasonr@matrix.org>
