macOS: Support diversion with a keyboard emulation

[MattHag]

Information

• Solaar version: 1.1.14RC
• Distribution: macOS

Is your feature request related to a problem? Please describe.
The existing implementation of Linux provides a dummy keyboard to fake inputs using evdev. The diversion of keys is not functional on macOS, rendering man rules unusable.
However, to fix this for macOS it requires a good understanding how the diversion works and how to keep it compatible with Linux rules as best as possible.

Describe the solution you'd like
There's no equivalent for macOS, but pyobjc with CGEventCreateKeyboardEvent and similar functions could be useful.

Describe alternatives you've considered

• Fake a whole HID device, if there's a library
• Use macOS scripting with osascript

Additional context
Add any other context or screenshots about the feature request here.