Add graphql reactive engine sig

sig/datadog/appsec/contrib/graphql/reactive/execute.rbs

@@ -0,0 +1,12 @@
+module Datadog
+  module AppSec
+    module Contrib
+      module GraphQL
+        module Reactive
+          module Execute
+          end
+        end
+      end
+    end
+  end
+end

sig/datadog/appsec/contrib/graphql/reactive/resolve.rbs

@@ -0,0 +1,17 @@
+module Datadog
+  module AppSec
+    module Contrib
+      module GraphQL
+        module Reactive
+          module Resolve
+            ADDRESSES: ::Array[String]
+
+            def self.publish: (Datadog::AppSec::Reactive::Operation op, Datadog::AppSec::Contrib::Rack::Gateway::Request gateway_resolve) -> boolish
+
+            def self.subscribe: (Datadog::AppSec::Reactive::Operation op, Datadog::AppSec::Contrib::GraphQL::Gateway::Resolve waf_context) -> void
+          end
+        end
+      end
+    end
+  end
+end