Add --no-audio support to VM spec (#460)

tart run supports --no-audio to disable host audio pass-through, but
there was no way to request it through a VM's spec - Headless, Nested,
and Suspendable all have a flag/field but audio didn't. Useful on
headless hosts with no audio hardware, where audio pass-through can
make guest CoreAudio depend on host audio services that don't exist.

pkg/resource/v1/v1.go

@@ -32,6 +32,7 @@ type VM struct {
 	NetBridged      string          `json:"net-bridged,omitempty"`
 	Headless        bool            `json:"headless,omitempty"`
 	Nested          bool            `json:"nested,omitempty"`
+	NoAudio         bool            `json:"noAudio,omitempty"`
 
 	VMSpec
 	VMSpecReadOnly