LibJS: Replace the boolean argument of Object::set with an enum class

This is more serenity-esque and also makes pointing out missing
exception checks during reviews much easier.

Userland/Libraries/LibJS/Runtime/Reference.cpp

@@ -21,7 +21,7 @@ void Reference::put_value(GlobalObject& global_object, Value value)
             throw_reference_error(global_object);
             return;
         }
-        global_object.set(m_name, value, false);
+        global_object.set(m_name, value, Object::ShouldThrowExceptions::No);
         return;
     }