Add DriverKit support

[egorzhdan]

Summary

This patch is the first in a series of patches to upstream the support for Apple's DriverKit. Once complete, it will allow targeting DriverKit platform with Clang similarly to AppleClang.

This code was originally authored by JF Bastien.

[egorzhdan]

Fix clang-format warnings in the added code

[arphaman]

Can you add a test case that verifies that using driverkit without a version will default it to driverkit19?

[egorzhdan]

• Add unit-tests to verify that DriverKit version defaults to 19
• Use DriverKit 20 as a minimum available version on arm & add a test for it

[arphaman]

LGTM