Rector has stable release, can we merge this now?

This could be merged, but needs updating i think in regards to the version numbers it seems, we'd want to work from stable right?

Yes, and I think PHP ^7.4 is supported, so change in .github/workflows/functional_test__rector_examples.yml is not needed
Also releasing Drupal rector 2.0 should be considered, following rector 2.0 and also phpstan-drupal 2.0

I bumped the rector dependency to ^2.0.

I agree with @Holo96 that it would be nice to have drupal-rector 2.0 to match phpstan-drupal 2.0 and rector 2.0.

Maintainers, please feel free to edit this MR however you like; as stating in the first post, I opened this as an experiment to test the feasibility of moving to phpstan 2.0.

Ok, i did some things to make compativbility happen.

Right now it tests on 1 and 2, since it seems that might juist be possibel. Unfortunately it seems that AnnotationToAttribute rector breaks in phpstan 2 right now. There might be more breaking tests.

I'm considering also to drop Drupal8 support, but not sure yet if that is needed.

Fixed a few more things thta were weird. Only real issue remaining is the broken AnnotationToAttributeRector