RFC Add namespaces support

[SerafimArts]

At the moment all GraphQL types share one global namespace. This is also true for all of the fields in mutation/subscription type. It can be a concern for bigger projects which may contain several loosely-coupled parts in a GraphQL schema.

It is suggested to reserve a symbol / for the support of the namespaces:

interface Common/Versioned {
  id: String!
  version: Long!
}

type Blog/Article implements Common/Versioned {
  id: String!
  version: Long!
  title: String!
  text: String
  author: Author
}

[SerafimArts]

Since version 1.2 the following keywords will be reserved:

• namespace
• import
• from
• use