LibJS: Mark Value as a trivial type for AK collection purposes

It's perfectly fine to memcpy() a bunch of JS::Values around, and if
that helps Vector<Value> go faster, let's allow it.

Userland/Libraries/LibJS/Runtime/Value.h

@@ -735,6 +735,7 @@ struct Formatter<JS::Value> : Formatter<StringView> {
 template<>
 struct Traits<JS::Value> : DefaultTraits<JS::Value> {
     static unsigned hash(JS::Value value) { return Traits<u64>::hash(value.encoded()); }
+    static constexpr bool is_trivial() { return true; }
 };
 
 }