Refactor taxonomy hierarchy plugin for performance

Converted the last patch #8 to MR, with some minor fixes added.

Great work, it looks good, with that said, facets has quite a lot of phpstan warnings.

Can someone also fix this one? We need to resolve some of these phpstan issues that relate to deprecated calls affecting php 8.2+.

Please see related issue
🐛 Use of dynamic properties is deprecated in PHP 8.2+ Active

I'd be happy to help on those, but these are not strictly related to this issue are they?

no not directly related but should be fixed asap

Let's wait for 3502957 and once that goes in, update the merge request with the latest commits to the head of 3.0.x-dev and then re-verify the pipeline results at that time.

📌 Fix PHPStan issues reported on CI/gitlab Active