feat: Add strictVisibility check option to ByRole queries

[benlesh]

What:

Added an option called strictVisibilityCheck that defaults to true (for now). If true it will use the existing code path that does a getComputedStyle on each node to check visibility during queries ByRole. If set to false, the visibility check settles for a more lose algorithm that doesn't run getComputedStyle.

Why:

This is being added as a means of improving performance of tests using queries like getAllByRole on larger sets of DOM elements, as can be found in many real-world applications. Anecdotally, using this setting fixed one test I had locally from 8000ms to 500ms total. (still not great, but miles better).

How:

Added an option to the type definition, threaded it through the existing logic, and added a "loose" check for inaccessibility. I added a test with a few checks to make sure the default is still working as expected, and the new setting still works in a similar manner.

It's worth noting that I tried to add a test that checked "indirect" visibility alterations through CSS classes, however, I was unable to get the test harness to recognize the CSS class and trigger layout (I was probably doing something wrong there, happy to follow up).

Checklist:

• Documentation added to the
  docs site
• Tests
• TypeScript definitions updated
• Ready to be merged
  

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[eps1lon]

I don't want to define any custom interpretation what it means to be in the a11y tree. This will be hard to teach and probably change too often depending on the performance needs. Users should use the hidden option instead if they don't want to check if an element is in the a11y tree or not.

[benlesh]

hidden: true isn't quite accurate to the need, but whatever. Not my library. I'll fork it if I need this consistently, I guess.