[Parent task]
Add REST endpoints to the OAuth extension that allow users of the API Portal to:
- List their clients and view client details
- Create a client (T251280)
- Reset client secret (T254200)
Disable an OAuth client(T254200) - deprioritized for now
In addition, add functionality that allows to us enable the endpoints in beta for testing before enabling them in production, via
experimentalRoutes.json.