icon slot for each item

[jachin]

Support an icon for each option in the dropdown.

It should also show up when an item is selected.

It would be nice to use a slot here, but that's not going to work since we need these icons to show up at least 2 places (in the dropdown and in the selected value element).

We're probably going to need to do node cloning here.

The markup would look something like...

<select slot="select-input">
  <option data-description="scarlet, vermilion, ruby, ruby red, ruby-colored, cherry" selected="">
    <span class="icon">....</span>
    Red
  </option>
  <option data-description="yellowish, yellowy, lemon, lemony, amber, gold, golden; blond, light brown, fair, flaxen">
    <span class="icon">....</span>
    Yellow
  </option>
  <option data-description=" sky blue, azure, cobalt (blue), sapphire, cerulean, navy (blue), saxe (blue), Oxford blue, Cambridge blue, ultramarine">
    <span class="icon">....</span>
    Blue
  </option>
  <option data-description="A town in France">
    Orange
  </option>
  <option data-description="greenish, viridescent; olive green, pea green, emerald green, lime green, bottle green">
    Green
  </option>
  <option data-description="violet">
    Purple
  </option>
</select>