Field group support

#3278537: D10 compatibility | Declaration of Drupal\field_group\Routing\RouteSubscriber::getSubscribedEvents() must be compatible with Drupal\Core\Routing\RouteSubscriberBase::getSubscribedEvents() is in, so we can start testing field group with DS and add the tests back.

Marking critical because field group support is probably broken completely

This works, however, might be bitten by #3120298: Order of alter hooks is not always respected by ModuleHandler.

So even if the tests are green now (probably after commit), let's hope that the module implements thing is just something weird in the test only :)

committed, hoping that the module order is something weird in the tests, so leaving for now though.