Although we are phasing out our support of OIDC, this particular feature will allow us to eliminate many of the settings we
share across services. Instead of reading various endpoints and secret keys from settings or hardcoded values, services
with the proper authentication backend can simply read (and cache) the information from this endpoint.

ECOM-3629

Move oauth_dispatch from lms to openedx/core.

* Created URL route
* Expanded test code to confirm expected behavior

MA-2124

Available backends:

* django-oauth-toolkit (DOT)
* django-oauth2-provider (DOP)

* Use provided client ID to select backend for
  * AccessToken requests
  * third party auth-token exchange
* Create adapters to isolate library-dependent functionality
* Handle django-oauth-toolkit tokens in edX DRF authenticator class

MA-1998
MA-2000