a11y: Add aria-label to mini badges below user avatars

Summary:
Links should have a discernible name per https://dequeuniversity.com/rules/axe/4.10/link-name
Thus re-use the existing tooltip text with the name of the badge as the `aria-label` text for the badge's <a> link.

Ref T16072

Test Plan:
Set up a badge at http://phorge.localhost/badges/.
Award badge to some user at http://phorge.localhost/people/badges/1/.
Make that user who received a badge comment on a Maniphest task.
Hover over the badge below the user avatar next to the comment to see the badge name.
Inspect the `<a>` element surrounding the badge icon below the user avatar next to the comment, see an `aria-label` also set to the badge name.
Optionally, run an Accessibility check in Chromium Lighthouse.

Reviewers: O1 Blessed Committers, chris

Reviewed By: O1 Blessed Committers, chris

Subscribers: tobiaswiese, valerio.bozzolan, Matthew, Cigaryno

Maniphest Tasks: T16072

Differential Revision: https://we.phorge.it/D26048

src/view/phui/PHUIBadgeMiniView.php

···
       'class' => implode(' ', $classes),
       'sigil' => 'has-tooltip',
       'href'  => $this->href,
+      'aria-label' => $this->header,
       'meta'  => array(
         'tip' => $this->header,
         'align' => $this->tipDirection,