Run OpenVSX registry without GitHub OAuth2 configuration

[svor]

Currently it's mandatory having GitHub OAuth configuration in the application.yaml:

  security:
      oauth2:
        client:
          registration:
            github:
              client-id: dummy
              client-secret: dummy

As an admin of the private internal registry, I’d like to run it without requiring OAuth configuration and to hide or disable the PUBLISH and Log In buttons in the UI:

In this case, only the ovsx CLI will be used to manage extensions in the registry.