Draft: feat(oidc): Switch API from Drupal OAuth to use Keycloak in its place

• feat(oidc): Switch API from Drupal OAuth to use Keycloak in its place

As part of the migration away from drupal auth, openvsx is one of the 3 remaining services that use the oauth server in the API stack. With only 1 main consumer, this should be a relatively simple switch over.