Generic macOS support

[cfergeau]

Support for macos guests was added in #148
Several features were unimplemented (see the corresponding section in #148), and it’s not tested in CI.

Fairly vague issue, but it would be good to make macos guests better :)

[cfergeau]

From #148, what’s missing, and what we need to decide whether it makes sense or not in vfkit:

• Downloading .ipsw restore images and creating new base install images
• Audio, since vfkit hasn't implemented it yet.
• VZMacKeyboardConfiguration (macOS 14+) or VZMacTrackpadConfiguration (macOS 13+)
• Various features requiring macOS version 14+:
  • saveMachineStateTo
  • restoreMachineStateFrom
• Testing macOS vms similar to the existing puipui-linux tests
• Figure out how to handle metadata. Other projects like macosvm and Tart create .json files with the VM's hardwareModel and MachineIdentifier values.

[cfergeau]

Note that macos guests don’t support nested virtualization, which makes them less interesting for some usecases (such as testing vfkit on different macos versions)