Implement schema coordinate spec as of 2025-06-06 (#4432)
This PR is applied to the `schema-coordinates` branch PR here: https://github.com/graphql/graphql-js/pull/3044
Implements schema coordinate spec changes per the June 5th 2025 WG discussion
https://github.com/graphql/graphql-spec/pull/794
- Add support for meta-fields (e.g. `__typename`)
- Add support for introspection types
- Revert back from FieldCoordinate+ValueCoordinate -> MemberCoordinate
cc @benjie
