This PR resolves #424, including:

• renaming of some elements for clarity (IconWrapper becomes PictoWrapper, createIcon becomes createPicto, etc.)
• Tile component can now use native DSFR pictograms with the pictogram prop, which is an exclusive property, alternative to imageUrl and its variations. I did not change any of the previous behavior, it's a plus.
• Tile tests
• the pictogram proo has it's own section in the Tile story

import CityHall from "@codegouvfr/react-dsfr/picto/CityHall";

<div
  className="container"
  style={{
    width: 360
  }}
>
  <Tile
    enlargeLinkOrButton
    linkProps={{
      href: '#'
    }}
    orientation="vertical"
    pictogram={<CityHall />}
    title="Intitulé de la tuile"
    titleAs="h3"
  />
</div>