Use PHP attributes instead of doctrine annotations for plugin type definitions

Used rector for the initial conversion, but there was still quite a bit of work still needed to get the code style and other things right.

I merged the latest dev release. Let's see if all the tests pass with this change.

#3 Yep, I saw that rector did not do a great job with the attribute code style. Thank you for doing the manual cleanup up

I am able to replicate the failing tests but can't determine why they are broken with these changes.