Proposal: Support modification and restore to the original value.

[unadlib]

After the draft function is executed, if the draft tree has not really changed its values, it should return to its original state.

Although Mutative and Immer behave the same behavior, we are considering supporting new behavior, as it can reduce some unexpected shallow comparison performance due to changed states(serializes to the same string).

For example,

const baseState = { a: { b: 1 } };
const state = produce(baseState, (draft) => {
  delete draft.a.b;
  draft.a.b = 1;
});
expect(state).not.toBe(baseState); // They should be equal.