Missing unsetAccessToken() implementation in OAuth2Storage causes RuntimeException

When revoking an access token, the OAuth2 library expects the storage class to implement unsetAccessToken().
However, Drupal\oauth2_server\OAuth2Storage does not implement this method, resulting in a runtime exception:

RuntimeException: Token storage Drupal\oauth2_server\OAuth2Storage must implement unsetAccessToken method in OAuth2\ResponseType\AccessToken->revokeToken()

Proposed solution:

• Implement the missing unsetAccessToken() method in OAuth2Storage
• Use existing storage logic to load and delete the token