Disable property invariance checks for properties with templates

[AndrolGenhald]

Very much a work in progress, comments welcome.
Fix for #5371

I would like to have property invariance checks work correctly, but for now I'll at least settle for disabling them for properties containing a template.

So far I've changed Union::hasTemplate to check for arrays, lists, class-string-maps, and iterables containing templates, and the tests all pass. If this is the desired behavior of hasTemplate there's also TGenericObject, and possibly TCallable and others I haven't considered yet.

Any advice is much appreciated. I'm also trying to figure out how to update ClassAnalyzer.php:708 to check if $guide_property_storage has a template that's used by $property_storage, and then maybe clone $guide_property_storage and set the template to what $property_storage has before doing the ->equals check, but I bet there's a better way to do that, cloning doesn't sound great for performance.

[AndrolGenhald]

Simplified now with getChildNodes() which I'd overlooked before, but it breaks a test for #3407. I think some checks are disabled for types with templates and now it's skipping checks that used to work properly? Also, hasTemplateOrStatic probably has the same issues as hasTemplate, but it's only used in one place and I don't understand it well enough to write a failing test case.

[AndrolGenhald]

I think this is working properly now to disable property invariance checks for templates, I'll open a new pull request if I manage to get the checks to work correctly with templates.

[muglug]

Thanks!