Summary: Form elements should have associated labels per https://www.w3.org/WAI/tutorials/forms/labels/ Ref T16072 Test Plan: Have a custom field of `"type": "date"` defined in `/config/edit/maniphest.custom-field-definitions/`. Go to edit a task (`/maniphest/task/edit/1/`) whose form exposes that custom field. Inspect the `<a>` field parameters with `class="calendar-button"` and see an additional `aria-label="Calendar date picker"`. 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/D26046