fix: no more empty groups in generated svgs

[Onetchou]

When the DOM tree was parsed to remove empty groups, the indexation of the QDomNodeList was being changed each time a node was deleted, to reflect the new state of the DOM tree. The code wasn't taking this into consideration and empty nodes were missed.

Now I'm removing the empty groups 1 by 1, starting the search over each time a node is deleted, to take into consideration the new indexation of the QDomNodeList.

There may be some more efficient ways of cleaning the empty groups, but this one is probably the easiest.

[what-the-diff]

PR Summary 🌟

• Simplified Clearout of Empty Groups🚮
  We've upgraded our original loop to a more effective while loop! This continues until every single empty group is gone, ensuring a cleaner experience even when the list alters while removing. Now we'll always have a tidy list, free from unnecessary emptiness!

• New Arrival - svgCleaned Flag🚩
  Say hello to our new friend - a boolean flag called svgCleaned. This clever little tool helps us keep track if we've removed any groups during an operation. This tiny yet powerful upgrade enhances the process of removing empty SVG groups. More efficiency, less chaos! 🎯

So, look forward to these changes that will help us perform better and keep things in order! 🌈

[Onetchou]

Fixes #1236

[DSCaskey]

Bravo. Looks good. No longer including empty / hidden labels..etc.