treewide: include PipeWire op and enforce PulseAudio check

This fully replaces PulseAudio with PipeWire and enforces the PulseAudio check and error message. The pipewire-pulse daemon is handled in the NixOS module.

Closes #26.

Signed-off-by: Ophestra <cat@gensokyo.uk>

hst/config_test.go

@@ -58,7 +58,7 @@ func TestConfigValidate(t *testing.T) {
 			Shell: fhs.AbsTmp,
 			Path:  fhs.AbsTmp,
 		}}, &hst.AppError{Step: "validate configuration", Err: hst.ErrInsecure,
-			Msg: "enablement PulseAudio requires PipeWire, which is not set"}},
+			Msg: "enablement PulseAudio is insecure and no longer supported"}},
 		{"valid", &hst.Config{Container: &hst.ContainerConfig{
 			Home:  fhs.AbsTmp,
 			Shell: fhs.AbsTmp,