Idea for discussion: Introduce `@gqlSchema.query`, `@gqlSchema.mutation` and `@gqlSchema.subscription`

[mandx]

These would tag a single object type as the type used in the corresponding schema declaration in the resulting SDL. So, something like this:

/**
 * @gqlType
 * @gqlSchema.query
 */
export class MyOddlyNamedQueryType {
  /** @gqlField */
  me(): string {
    return new 'yo';
  }
}

Would generate:

type MyOddlyNamedQueryType {
  me: String
}

schema {
  query: MyOddlyNamedQueryType
}

Same for @gqlSchema.mutation and @gqlSchema.subscription. Obviously, at build/introspection time, a check should run that asserts that each of these @gqlSchema.* appear only once. Defaults would still be used; so, there is a @gqlSchema.query on a type, but there's no @gqlSchema.mutation anywhere, it is assumed that the schema's mutation key would be whatever object type is named Mutation.