Improve floating element adaptive width api

[ycs77]

Changed

• Rename as prop to floatingAs
• Add as prop

If now as is

old rendered:

<button>
  <!-- reference element -->
</button>

<!-- `as` tag rendered start -->
<div>
  <!-- floating element -->
</div>
<!-- `as` tag rendered end -->

new rendered:

<!-- `as` tag rendered start -->
  <button>
    <!-- reference element -->
  </button>

  <!-- `floatingAs` tag rendered start -->
  <div>
    <!-- floating element -->
  </div>
  <!-- `floatingAs` tag rendered end -->
<!-- `as` tag rendered end -->

Usage

• React version: https://headlessui-float.vercel.app/react/adaptive-width.html
• Vue version: https://headlessui-float.vercel.app/vue/adaptive-width.html

Migration

Change as prop to floatingAs (React) / floating-as (Vue).

Linked issue

resolve #13