3956bd4cd6
This introduces an `extension` yaml key, similar to `extension_type` to the dynamic interface. The validator uses the key to find extensions. Test coverage added similar to the previous change. BUG=b/488345908 TEST=pkg/dynamic_modules/test/data and pkg/front_end/testcases/general/dynamic_modules Change-Id: I4c802663dfee9bf216c0b3dc0f0a0198b8a1fbaa Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/484024 Reviewed-by: Johnni Winther <johnniwinther@google.com> Commit-Queue: Sigmund Cherem <sigmund@google.com> Reviewed-by: Alexander Markov <alexmarkov@google.com>