goModel/goField/goExtraField/goEnum x protobuf API_OPAQUE

### What happened?

The Golang team introduced the [Go Protobuf: The new Opaque API](https://go.dev/blog/protobuf-opaque)

In it we closed public fields of the structure (instead, by making the Get/Set/Has/Clear{StructName} methods) and removed optional (pointer)

Because of this, mapping to Protobuf via these GraphQL directives will not work when using API_OPAQUE.

### What did you expect?

It may be worth modifying the directives to support fields as interfaces Get/Set/Has/Clear{StructName} methods