Remove RES and REF typedefs in favor of spelled out Ref<>

These typedefs don't save much typing compared to the full `Ref<Resource>`
and `Ref<RefCounted>`, yet they sometimes introduce confusion among
new contributors.

modules/visual_script/visual_script_builtin_funcs.cpp

@@ -989,7 +989,7 @@ void VisualScriptBuiltinFunc::exec_func(BuiltinFunc p_func, const Variant **p_in
 			}
 
 			if (p_inputs[0]->is_ref_counted()) {
-				REF r = *p_inputs[0];
+				Ref<RefCounted> r = *p_inputs[0];
 				if (!r.is_valid()) {
 					return;
 				}