Synchronize airplay volume

[SteveMicroNova]

What does this change intend to accomplish?

Does the same as #1063, but for airplay Airplay does not allow outside sources change the volume of the airplay host, so it's a one way street this time

Checklist

• [ ] Have you tested your changes and ensured they work?
• [ ] Have you checked to ensure there aren't other open Pull Requests for the same update/change?
• [ ] If applicable, have you updated the documentation/manual?
• [ ] If applicable, have you updated the CHANGELOG?
• [ ] Does your submission pass linting & tests? You can test on localhost using ./scripts/test
• [ ] Have you written new tests for your core features/changes, as applicable?
• [ ] If this is a UI change, have you tested it across multiple browser platforms on both desktop and mobile?

[SteveMicroNova]

This will require some internal debate before merging, but I'm going to suggest this is ready for review even if not ready for merging