Provide DataLoader registry

[bkuberek]

Currently, the GraphqlPostHandler constructs an ExecutionInput and executes the graphql query without providing an option for user provided DataLoaderRegistry

light-graphql-4j/graphql-router/src/main/java/com/networknt/graphql/router/handlers/GraphqlPostHandler.java

Line 89 in 808682f

ExecutionInput executionInput = ExecutionInput.newExecutionInput().query(query).operationName(operationName).context(exchange).root(exchange).variables(variables).build();

When using DataLoader we need to set dataLoaderRegistry

ExecutionInput executionInput = newExecutionInput()
    .query(query)
    .operationName(operationName)
    .context(exchange)
    .root(exchange)
    .variables(variables)
    .dataLoaderRegistry(registry) // <---
    .build()

---

Alternatively, we should be able to use Instrumentation.instrumentExecutionInput(input, parameters), but there is a bug in graphql graphql-java/graphql-java#1667

It is still possible to do it via instrumentation but I think data loader registry could be added to router.

[stevehu]

I totally agree. This is a new feature added to the graphql-java lately. Would you be able to submit a PR for this? Thanks.