Proposal: support multiple mark function

[unadlib]

mark option is used to customize either mutable or immutable data. To make it pluggable, we might consider allowing it to support multiple functionalities.

For example,

const immutable = Symbol.for("immutable");

const mutableMark = (target, types) => {
  if (target[immutable]) {
    return types.immutable;
  }
};

const state = create(
  data,
  (draft) => {
    draft.foobar.text = "new text";
  },
  {
    mark: [
      mutableMark,
      (target, { mutable }) => {
        if (target === data.foobar) return mutable;
      }
    ],
  }
);