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.
* Allow creating VMs with implicit CPU and memory
* Clarify why cpu/memory can be 0 a bit better
* Controller(API): don't forget to update DefaultCPU and DefaultMemory
* Add an integration test for implicit CPU and memory
kylefuhrmanncalm