Clarify aria-required-parent/child message for presentation conflict

[WilcoFiers]

the following code creates a somewhat confusing remediation message:

<ul role="tablist">
  <li role="presentation" aria-hidden="false">
    <div role="tab" tabindex="0" aria-selected="true">Tab 1</div>
  </li>
</ul>

## aria-required-children:
Fix any of the following:
- Element has children which are not allowed: [role=presentation]
- Element uses aria-busy="true" while showing a loader

## aria-required-parent:
Fix any of the following:
- Required ARIA parent role not present: tablist

Using [role=presentation] is just fine here, the issue is with the global attribute. The issue is that the presentation role is ignored because of aria-hidden. We should have an explicit message explaining this in both rules.

[straker]

It also should give an presentation-role-conflict violation which tells you about the conflict, though the message is a bit confusing as well ("does not have global ARIA attribute"?)

"Fix all of the following:
  Element does not have global ARIA attribute"

Do we need to tell the user 3 times that the role is ignored?