Tests:
Test 1
Authors MUST NOT use any role or aria-* attribute on the label element when it
associted with a labelable element.
Expected result:
error or warn for inappropriate use of the role and any aria-* attribute when the
label element is used to label a labelable element.
Test 2
Authors MAY use any allowed role or aria-* attribute on the label element if it is not labeling a labelable element.
Expected result:
this label element is not associated with a labelable element and thus authors MAY use any allowed roles and aria-* attributes to it.