`audio` element test

Pass Criteria

#1: Element is supported
#2: Element has correct HTML and Core Accessibility API mappings
#3: Controls are keyboard accessible:
- #3.1: Controls MUST be focusable
- #3.2: MUST be able to activate controls, including any child menu/controls

Reference

Test au-001: `audio` element

Test au-002: `audio` element with `aria-label`

Test au-003: `audio` element with `aria-label` and `aria-describedby`

Audio file: Spam call: Bob hangs up 7 mins into his survey by Bruce Lawson