feat(highlight-auto): include language in "on:highlight" event detail

[metonym]

Features

• include the inferred language name in on:highlight event detail

Fixes

• e.detail.highlighted is a string

<HighlightAuto
  code={`body {\n  padding: 0;\n  color: red;\n}`}
  on:highlight={(e) => {
    console.log(e.detail.language); // "css"
  }}
/>

[render]

Your Render PR Server URL is https://svelte-highlight-pr-252.onrender.com.

Follow its progress at https://dashboard.render.com/static/srv-cen2a1un6mph23a5pgj0.

[render]

Your Render PR Server URL is https://svelte-highlight-pr-252-5cw6.onrender.com.

Follow its progress at https://dashboard.render.com/static/srv-cen2a2mn6mph23a5pgn0.