feat: allow $state in computed class fields

[Ocean-OS]

Closes #17012.
As described here, the way we transform computed class fields is using a variable to deduplicate the key (to avoid side effects and the like):

// before
let i = 0;
class Foo {
  [i++] = $state(0);
}
// after
let i = 0;
var Foo = (() => {
  let key;
  return class Foo {
    #_ = $.state(0);
    get [key = i++]() {
      return $.get(this.#_);
    }
    set [key]($$value) {
      return $.set(this.#_, $$value, true);
    }
  }
})();

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Latest commit: 307e42f

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