Zephyr as a UOS

[rossburton]

It would be neat to have an example that built a sample application using Zephyr as a guest.

[ChinHuatAng]

See Geoffroy's Zephyr UOS demo: https://www.zephyrproject.org/demos/zephyr-rtos-application-running-on-acrn-hypervisor-on-an-intel-nuc/

Official Zephyr UOS documentation: https://projectacrn.github.io/latest/tutorials/using_zephyr_as_uos.html

Probably update/reuse meta-zephyr: http://git.yoctoproject.org/cgit/cgit.cgi/meta-zephyr/