`button` element

Pass Criteria

#1: Element is supported
#2: Correct HTML and Core Accessibility API mappings
#3: Correct Accessible Name & Description Calculation

Reference

Test btn-001: `button` element, no text

Test btn-002: `button` element, with text

Test btn-003: `button` element, with `disabled` attribute

Test btn-004: `button` element, with accessible name from `aria-label` attribute

Test btn-005: `button` element, with text and `aria-label` attribute

Test btn-006: `button` element, with text and `aria-label` attribute and `aria-pressed="true"`