Request - Input meter and output test buttons in Sound panel

[AlexisSweetMcKay]

Ubuntu has a feature where a user can manually test the left and right output channels for audio output devices, and it has an active meter displaying levels for input devices. Cosmic lacks this functionality, meaning users can't test standard ports on their devices in an offline environment.
It would be useful and appreciated if that functionality was implemented in Cosmic.

[leviport]

Being tracked here: pop-os/cosmic-settings#1901