Feature request: Select devices to be muted

[AdamXweb]

Hi!

Thanks for supporting automute after all these years.
I have a suggestion to allow the user to define which audio inputs should be muted.

e.g. If my mac is docked, then i'll have an external DAC which I don't mind staying unmuted if it goes to sleep, however if its my MacBook speakers or headphones, then i'd always want them to mute.

Happy to test a branch if you need some feedback!

[AdamXweb]

Further to this, would be good to select if this should target just the inbuilt speakers vs external device.