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.

[vulpes2]

CoreHID has exactly what you want, the only caveat is that it's only available on Sequoia (or newer). We can restrict this feature to Sequoia at first and then think of a fallback later if there's demand for that. For older macOS versions I think you'd need to write an actual driver for virtual HID stuff, which is probably not worth the effort.