node and nodes scalar type configuration

[crpahl]

PR Description

This PR makes it possible to configure the node and nodes scalar type through the Configuration class.

For example, you could do this in a Rails initializer:

GraphQL::Configuration.relay_node_id_type = "SomeScalar"

And the arguments to node and nodes would be id: SomeScalar! and ids: [SomeScalar!]! respectively. The returned id field would be id: SomeScalar!.

Why is this needed?

We don't use the GraphQL Ruby ID scalar and instead use our own scalar for ID fields. Maybe we should consider going back to the ID scalar, but that's a different discussion/concern for if we ever want to go back in that direction 😄 This PR makes it possible to use our own scalar for the root node and nodes field.

GraphQL Ruby doesn't support this type of configuration?

I ultimately need to be able to set the scalar type at Ruby load time. Here for example:

child_module.field(:id, Configuration.relay_node_id_type, null: false, description: "ID of the object.", resolver_method: :default_global_id)

And setting this in a configuration class was the easiest way for me to do this through a simple Rails initializer. I realize this isn't a pattern that GraphQL Ruby takes for configuration (unless I missed it!) and I'm open to any other approaches!

Other approaches we considered

I realize I could also completely override the modules, but it felt much better to be able to configure/inject the type and save us from awkward monkey patching.