Prepare for protobuf editions support

[ascopes]

When I have time, I need to review the details of https://protobuf.dev/editions/overview/ and ensure we do not need to do anything in the plugin to continue to support Protobuf as it moves from proto2/proto3 to editions support.

This should if possible include support for prototiller once available.

Existing functionality must be kept.

It is likely we do not need to do anything with this, but it needs to be checked.

[ascopes]

This appears to not need any change for now, so closing.