Removing warning for new fields in GraphQL schemas

If you add schema fields and run sanity graphql deploy you will no longer be warned about “dangerous changes.” Previously, our GraphQL validation followed the behavior of graphql.js, which treats added fields as “dangerous.” We have had a lot of feedback, that in practice, it has been more bothersome than useful.

• Since v2.16.0, (inline) references in Portable Text would not be saved properly and left an arbitrary attribute. This version fixes that.