Improve debugging/developer experience with rest_log module

You cannot add dev-dependencies in libraries in composer. well you can, but it would have no affect.
I think it might work to "suggest" it via composer suggest option + we can add it to our documentation.

I added the rest log in require-dev and suggest in composer.json.

For checking api requests I've added a request check:

  protected function isApiResponse(Request $request): bool {
    return $request->attributes->get('lupus_ce_renderer') || $request->getRequestFormat() == 'custom_elements';
  }

I've also been considering some other ways, but this seemed the most straightforward. The module now works just on on/off - if enabled it logs and if not it doesn't. I think that for development experience this is enough.

@fago @useernamee can you guys familiarize with my last comment in rest log mirror issue( https://www.drupal.org/project/rest_log/issues/3432400#comment-15563623 ✨ Add support for Lupus Decoupled Drupal Needs review ) and update your merge request with needed changes?

Implemented the change from ✨ Add support for Lupus Decoupled Drupal Needs review

looks all good to me! however, the gitlab pipeline is failing with the changes. we need to make it accept it.