As a Magento developer, I want a convenient way to extend GraphQL and implement my own GraphQL endpoints so that I'm not constrained by the out-of-the-box implementation of GraphQL.

Use Cases
3rd party developer can:

• expose simple entities via schema declarations only, without writing PHP code
• for complex entities, you can do this with few resolver changes
• extend GraphQL module
• implement GraphQL endpoints
• create or modify classes to alter schema reading/generation
• extend the testing framework