SCIM discovery and ResourceTypes listing

## What

SCIM discovery/ResourceTypes: provider discovery change and types not listed in ResourceTypes still being queried.

## Want

- SCIM discovery/ResourceTypes: provider discovery change
- Types not listed in ResourceTypes still being queried

## Ideas this came from

- [#24228 SCIM provider dsicovery change](https://github.com/goauthentik/authentik/issues/24228) — The SCIM provider currently sets users/groups discovered in a sync, that also exist in authentik, as provisioned users/groups. Add a check so that ONLY users/gr
- [#24486 SCIM: types not listed in ResourceTypes queried anyway](https://github.com/goauthentik/authentik/issues/24486) — A SCIM Sync always calls /Groups even if it's not supported. For this application, that endpoint always returns a 404, aborting the full sync. /ResourceTypes fo

Start by reading the linked issues #24228 and #24486, then trace the SCIM provider discovery flow and the /ResourceTypes and /Groups requests described here. Done means discovery uses the provider's supported resource types, unsupported types are not queried, and the sync still handles supported users and groups correctly.

Written by the indexing model from the issue text.