feat: use cosmic-settings-daemon audio API

[mmstick]

Requires pop-os/cosmic-settings-daemon#135

This changes the behavior of cosmic-osd confirm-headphones to enable the settings daemon to take over the responsibility of selecting and applying profiles and their routes on behalf of cosmic-osd. The settings daemon will call cosmic-osd confirm-headphones --device ID to request a dialog and then cosmic-osd may use the device ID as an input to either SelectHeadphoneProfile or SelectHeadsetProfile. The settings daemon can then make better decisions about what to do since it's already tracking everything.

This will also drop the dependency on libpipewire, libpulse, and the cosmic-settings pulse subscription. The audio server events for the volume OSD notifications will now come from the settings-daemon's varlink API as well.

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[jklgrasso]

I guess I missed that this requires another PR. It looks like pop-os/cosmic-settings-daemon#135 still has some work going on. I'll unassign myself for now