Support for OAuth introspection

I've written a ui-connctor enhancement for a customer that includes using a config variable to drive the use of OAuth introspection in the auth flow. I'd like to contribute this back to the code base.

Start by locating the ui-connector authentication flow and its configuration handling. Determine how the proposed config variable should control OAuth introspection, then identify the relevant existing tests or add coverage for both configuration paths. Done means the auth flow supports the requested configurable introspection behavior without breaking the existing path.

Written by the indexing model from the issue text.