Updated Web Platform Tests

Hi all,

I recently updated the Web Platform Tests to reflect the WebAuthn WD-05
spec changes and created a pull request:
https://github.com/w3c/web-platform-tests/pull/7500

The coverage is still not even close to comprehensive, but if people run
these tests and find that they are headed in the right direction it won't
take much time to get to much more comprehensive coverage. For what it's
worth, I've already run these against one of the browsers and found bugs --
so apparently they do have some value already. :)

I can't merge them in to WPT without a reviewer assigned, so if anyone
would be willing to review the PR please let me know.

Thanks,
Adam