Method XF\BbCodeRenderer\Html::getValidUrl should be in a utility class

[Kirby]

Affected version

2.2.13

Not really a bug, but a development annoyance that could be fixed easily:
Method XF\BbCodeRenderer\Html::getValidUrl can be useful in various places, but it's a protected method of the BB code renderer class.

It would be great if this was in a utility class instaead so it could be used everywhere.