[TASK] EXT: t3skin - .list-unstyled for ol & ul

Brings CSS class for lists that semantically need to be
UL or OL tags but do not have a visible list-style-item:

<ul class="list-unstyled">
	<li>…</li>
</ul>
<ol class="list-unstyled">
	<li>…</li>
</ol>

Resolves: #55834
Releases: 6.2
Change-Id: Ic51fbe1f0995b4504d5b10a4c83775a977a19e33
Reviewed-on: https://review.typo3.org/27801
Reviewed-by: Georg Ringer
Tested-by: Georg Ringer