macOS support

Port Monado on macOS (x86_64 and apple silicon)

The following items need to be done

• Basics
  • Document how to install all the requires dependencies
  • Adapt the CMakeFiles for macOS (Check APPLE or ${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
  • Use MoltenVK to run the compositor
  • XR_KHR_vulkan_enable/XR_KHR_vulkan_enable2 support for apps.
  • Open a simulator window
  • CI
• Nice to have
  • Find out how to share buffer handles between processes
    • https://developer.apple.com/documentation/kernel/iokit_fundamentals/memory
    • https://developer.apple.com/documentation/kernel/iobuffermemorydescriptor
  • Find a way to open an HMD device (anything like DRM leasing in macOS?)
    • Luckily libusb/hidapi work fine on macOS
    • https://developer.apple.com/documentation/kernel/hardware_families/graphics_and_displays
    • https://developer.apple.com/documentation/appkit/windows_panels_and_screens
  • Port the IPC
    • See if https://developer.apple.com/documentation/xpc is worth pursuing

Existing attempts/work to port Monado on macOS

• !1818
• https://github.com/shinyquagsire23/monado/commit/783c1413422799163766f621ba5e823ef2c15d9e (was not directly submitted and this isn't GPL so we would need a submission of this code to use it, can't just take it)

Any comment, feedback and interesting links are welcome.