Support Nested GraphQL Mutations

# Summary
This RFC outlines a proposal to implement support for nested Graphql Mutations.Nested mutations is the ability to perform mutations on a type other than the root type in GraphQL and how to define circular dependency schema files

# Motivation
Most developers find it easier to think of "changes" in a sequential fashion. Databases can and do perform many update/insert/delete transactions concurrently. Any modern databases exposing any API (including GraphQL) has to be ready for concurrently arriving requests as well as nested mutations

# Functional Specifications

Circular Reference

Nested Mutation Types

# Referene
Nested mutations have been https://github.com/graphql/graphql-spec/issues/252 but not yet approved

Inizia esaminando la proposta sulle mutazioni annidate e la issue #252 della specifica GraphQL a cui si fa riferimento. Non sono indicati alcun punto di ingresso dell’implementazione, file o test; chiarisci i requisiti relativi ai riferimenti circolari e alle mutazioni annidate prima di definire i test di accettazione e l’ambito dell’implementazione.

Scritto dal modello di indicizzazione a partire dal testo della issue.