Feature request: add labeled_by filter

[misaka]

Hi all.

I just discovered this package while migrating some tests from Playwright to Capybara, and it really looks nice! Thank you for sharing it!

The described_by filter seems particularly handy for writing tests without relying too directly on the HTML structure. In our project, however, we're using a component that uses the labeledby ARIA attribute which, I think, could work the same way.

Would adding a labeled_by filter that functions similar to described_by make sense? I'd also be up for taking a stab at adding it if so.

Cheers!

[seanpdoyle]

Conceptually, is labeled_by backed by the aria-labelledby attribute? If that's the case, would the newer accessible_name cover that style of filtering?