Add more complicated GraphQL project as an example

[wKich]

We need to show different use cases:

• Using 3rd party APIs in custom resolvers or/and data loaders
  • Fetch data from custom resolver
  • Use 3rd party API in data loaders
• Generate types and use them in different contexts
  • Async resolvers which return NodeId or part of object/interface fields
  • Custom resolvers with complex logic, that couldn't be implemented by @field/resolve directives
  • Client queries
• Generate client's SDK from output GraphQL schema
• Implement GraphQL type graph with type inheritance (using @implements/discriminates directives), resolve fields from different sources