Test for conformant RBAC management

### What problem are you facing?

Crossplane includes an RBAC manager that manages RBAC roles for both Crossplane controllers (e.g. to enable composition and providers to function) and users (e.g. to create roles like `crossplane-admin`). Deploying the RBAC manager is optional, but I'm not sure whether we should allow distributions of Crossplane to omit it completely.

### How could conformance help solve your problem?

We should determine whether we should test for RBAC manager conformance, and what exactly we're testing for, then write the tests. Perhaps we could test for only `Basic` mode support (i.e. the permissions required for Crossplane controllers to function).

Start by reviewing Crossplane's RBAC manager and the permissions required for controllers to function in Basic mode. Decide whether RBAC manager conformance is required and define the exact behaviors to test. Done means the conformance criteria are agreed and automated tests cover the selected RBAC support.

Written by the indexing model from the issue text.