fix: removeHiddenElems - treat <path> with opacity:0 as non-rendering node.

[johnkenny54]

removeHiddenElems was removing all <path> elements with opacity:0. If the path was referenced by a <textPath>, this caused the text to disappear.

This resolves 10 regression errors:

svgs/oxygen-icons-5.113.0/scalable/apps/digikam.svg     pass
svgs/oxygen-icons-5.113.0/scalable/apps/showfoto.svg    pass
svgs/oxygen-icons-5.113.0/scalable/apps/small/16x16/digikam.svg pass
svgs/oxygen-icons-5.113.0/scalable/apps/small/16x16/showfoto.svg        pass
svgs/oxygen-icons-5.113.0/scalable/apps/small/22x22/digikam.svg pass
svgs/oxygen-icons-5.113.0/scalable/apps/small/22x22/showfoto.svg        pass
svgs/oxygen-icons-5.113.0/scalable/apps/small/32x32/digikam.svg pass
svgs/oxygen-icons-5.113.0/scalable/apps/small/32x32/showfoto.svg        pass
svgs/oxygen-icons-5.113.0/scalable/apps/small/48x48/digikam.svg pass
svgs/oxygen-icons-5.113.0/scalable/apps/small/48x48/showfoto.svg        pass

[SethFalco]

LGTM! Happy to see tests for both, when path is referenced and not referenced too. 👍🏽

Thanks for spotting the issue and submitting a patch.