Add Translucent Icon for MacOS

Summary

I've added a new icon for MacOS so that the indicator changes color depending on whether a device is connected. I copied the style of the Wireguard icon; the #000000 color is used but with 50% opacity. This ensures the icon displays correctly in both dark and light themes.

I decided to add a systrayActiveHook method to the helper as there's an extra bit of logic and an extra instance variable needed for the Mac menubar to switch icons.

After:

No devices connected	Devices connected