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

Commencez par examiner la proposition de mutations imbriquées et l’issue #252 de la spécification GraphQL référencée. Aucun point d’entrée d’implémentation, fichier ou test n’est indiqué ; clarifiez les exigences concernant les références circulaires et les mutations imbriquées avant de définir les tests d’acceptation et le périmètre de l’implémentation.

Rédigé par le modèle d'indexation à partir du texte de l'issue.