fix(types): allow DirectiveArguments third parameter to accept undefined

[Mini-ghost]

When I tried to edit my component, I encountered a type error:

const InputComponent = defineComponent({
  render() {
    return withDirectives(
      createElementBlock(
        'input',
        {
          'onUpdate:modelValue': (event: string | number) =>
            (modelValueWritable.value = event),
          readonly: props.readonly,
          disabled: props.disabled,
        },
        null,
        512
      ),
      [[vModelText, modelValueWritable.value, void 0, props.modelModifiers]]
    );
  },
});

The error message indicated that undefined cannot be assigned to type string:

Type 'undefined' is not assignable to type 'string'.

However, upon reviewing the code generated in the Playground and Vue's source code, I found that when DirectiveArguments has a length of 4, the third argument can indeed be undefined.

function render(_ctx, _cache, $props, $setup, $data, $options) {
  return _withDirectives((_openBlock(), _createElementBlock("input", {
    "onUpdate:modelValue": _cache[0] || (_cache[0] = $event => (($setup.msg) = $event))
  }, null, 512 /* NEED_PATCH */)), [
    [
      _vModelText,
      $setup.msg,
      void 0,
      { lazy: true }
    ]
  ])
}

Playground

This PR corrects the type definition to reflect this observation.

Thank you for taking the time to review this PR. If there's anything I overlooked, please let me know.

[github-actions]

Size Report

Bundles

File	Size	Gzip	Brotli
runtime-dom.global.prod.js	90.2 kB	34.6 kB	31.2 kB
vue.global.prod.js	147 kB	54.1 kB	48.1 kB

Usages

Name	Size	Gzip	Brotli
createApp	49.7 kB	19.5 kB	17.8 kB
createSSRApp	53.2 kB	21 kB	19.1 kB
defineCustomElement	51.9 kB	20.2 kB	18.5 kB
overall	63.2 kB	24.5 kB	22.3 kB