proposal; preset `mute` represents current status

[xerc]

sound OFF show touchBarAudioOutputVolumeHighTemplateName
sound ON show touchBarAudioOutputMuteTemplateName

MTMR/MTMR/ItemsParsing.swift

Lines 155 to 166 in dd99e9d

	"mute": { _ in
	let imageParameter = GeneralParameter.image(source: NSImage(named: NSImage.touchBarAudioOutputMuteTemplateName)!)
	return (
	item: .staticButton(title: ""),
	actions: [
	Action(trigger: .singleTap, value: .hidKey(keycode: NX_KEYTYPE_MUTE))
	],
	legacyAction: .none,
	legacyLongAction: .none,
	parameters: [.image: imageParameter]
	)
	},