GraphQL types models #13
Description
Current implementation of make_executable_schema knows how to work with current GraphQL types defined by library (and vanilla approach implemented in Ariadne proper).
To support different approaches for schema definitions (and mixing them), make_executable_schema should be changed to use some sort of contract with types to retrieve their requirements and GraphQL types definitions.
Proposed contract is for make_executable_schema to look for __get_graphql_model__ methods on types passed to it. This method would be expected to yield an instance of GraphQLModel sub-class that make_executable_schema would know how to construct GraphQL type from.