Consider making aria-treeitem-name a WCAG rule

Currently elements with role=treeitem, without an accessible name are failed as a best practice, instead of a WCAG rule. The reason for that was to account for static treeitems. It is hard to argue that those are failures of WCAG.

Another way we could have done that, which is more involved, but I think I would prefer is to make it a WCAG rule, and flag static treeitems for review, so that:

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