[css-forms-1] Some controls should be mentioned/included

[mfreed7]

There are a few controls that aren't mentioned in the spec draft, and probably should be:

Likely need some additional customizability and style standardization:

• <input type=button>
• <input type=reset>
• <input type=submit>
• <input type=email>
• <input type=tel>
• <input type=url>
• <input type=image>
• <fieldset>
• <legend>

These might be roughly "done" but perhaps should be included for completeness?

• <button>
• <output>
• <object>
• <img>
• <details>/<summary>

[lukewarlow]

<input type=button>
<input type=reset>
<input type=submit>

Should be partly addressed by #11875