clone support

[pi0]

Currently, we only create new object/array when both defaults and current value have a value while if only there is value here we set it.

I am thinking to introduce a new option to createDefu(merger, { clone: true } to enable cloning behavior.

An alternative would be using structuredClone however i think it also copies the values (non object/array) and taking more memory also not available in (at least Node) workers.