More ports from aria-toolkit and enhancements

* Implicit semantics
* More audits:
 * RequiredOwnedAriaRoleMissing
 * DuplicateId
 * RoleNotScoped
 * BadAriaAttribute
 * UnsupportedAriaAttribute
 * AriaOnReservedElement
* Fixed BadAriaRole audit to handle abstract roles
* Several supporting changes and optimizations to utility methods and constants.
* A few minor formatting tweaks

I'm not terribly familiar with xslt, but it looks like you've been a bit inconsistent with indenting. For example, there's an indent after call-template on line 52, but not here. Is that deliberate?