Deconstruct the interpreter

[rmosolgo]

This is mostly an exploration into the question, can runtime features be teased out (however ugly) of the existing execution code? If so, maybe GraphQL-Ruby could offer a mix-your-own runtime API.

Make it so that each of these can be opted in to (but all are on by default, for compatibility's sake):

• Query/multiplex instrumentation
• .trace
• Lazy values
• Object type instantiation / .authorized?
• Custom field resolution (instead, just call methods by field name)
• Returning errors / skip (source of many .is_a? checks)
• context[:current_....], source of many Hash#[]= calls
• others?

[rmosolgo]

I'm exploring these performance improvements by other avenues, for example, #4344 #4342 #4330