feat(Execution) add DeferredExecution, implement @stream and @defer

Author: rmosolgo

lib/graphql/directive.rb

@@ -41,5 +41,7 @@ def on_operation?
   end
 end
 
+require "graphql/directive/defer_directive"
 require "graphql/directive/include_directive"
 require "graphql/directive/skip_directive"
+require "graphql/directive/stream_directive"

lib/graphql/directive/defer_directive.rb

@@ -0,0 +1,5 @@
+GraphQL::Directive::DeferDirective = GraphQL::Directive.define do
+  name "defer"
+  description "Push this part of the query in a later patch"
+  locations([GraphQL::Directive::FIELD, GraphQL::Directive::FRAGMENT_SPREAD, GraphQL::Directive::INLINE_FRAGMENT])
+end

lib/graphql/directive/stream_directive.rb

@@ -0,0 +1,5 @@
+GraphQL::Directive::StreamDirective = GraphQL::Directive.define do
+  name "stream"
+  description "Push items from this list in sequential patches"
+  locations([GraphQL::Directive::FIELD])
+end

lib/graphql/execution.rb

@@ -1,2 +1,3 @@
+require "graphql/execution/deferred_execution"
 require "graphql/execution/directive_checks"
 require "graphql/execution/typecast"