[Question] Integration with nestjs (@nestjs/graphql)
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### Summary

How to integrate `Graphile` server with the `NestJS` application for single `Grapghql` endpoint. 

### Additional context

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So far I am able to integrate Postgraphile into the NestJS application, and I have a running Graphql endpoint and NestJS server endpoints. 

**Setup**
- Setup NestJS application
- Add Graphile server (using middle-ware option)
- Add `@nestjs/graphql` package
- Create custom endpoints in NestJS

**Question:** 
Is it possible that somehow I could merge `@nestjs/graphql` generated `schema.graphql` to graphile server to generate crud for these schema too? 

**Benefit**
This way I would have benefit of defining custom endpoints using awesome `NestJs` syntax and excellent performance/crud functionality of `Postgraphile`.

Please note that `NestJs` can generate schema of type `const schema: GraphQLSchema` for defined routes/resolvers. 

```ts
export class GraphQLSchema {
  description: Maybe<string>;
  extensions: Maybe<Readonly<GraphQLSchemaExtensions>>;
  astNode: Maybe<SchemaDefinitionNode>;
  extensionASTNodes: Maybe<ReadonlyArray<SchemaExtensionNode>>;

  constructor(config: Readonly<GraphQLSchemaConfig>);
  getQueryType(): Maybe<GraphQLObjectType>;
  getMutationType(): Maybe<GraphQLObjectType>;
  getSubscriptionType(): Maybe<GraphQLObjectType>;
  getTypeMap(): TypeMap;
  getType(name: string): Maybe<GraphQLNamedType>;

  getPossibleTypes(
    abstractType: GraphQLAbstractType,
  ): ReadonlyArray<GraphQLObjectType>;

  getImplementations(
    interfaceType: GraphQLInterfaceType,
  ): InterfaceImplementations;

  // @deprecated: use isSubType instead - will be removed in v16.
  isPossibleType(
    abstractType: GraphQLAbstractType,
    possibleType: GraphQLObjectType,
  ): boolean;

  isSubType(
    abstractType: GraphQLAbstractType,
    maybeSubType: GraphQLNamedType,
  ): boolean;

  getDirectives(): ReadonlyArray<GraphQLDirective>;
  getDirective(name: string): Maybe<GraphQLDirective>;

  toConfig(): GraphQLSchemaConfig & {
    types: Array<GraphQLNamedType>;
    directives: Array<GraphQLDirective>;
    extensions: Maybe<Readonly<GraphQLSchemaExtensions>>;
    extensionASTNodes: ReadonlyArray<SchemaExtensionNode>;
    assumeValid: boolean;
  };
}
```

I am using latest NestJS and Postgraphile. 