xen: implement Xen domain control interface

Add Xen domctl API implementation for Zephyr as control domain.

Previously Zephyr OS was used as unprivileged Xen domain (Domain-U),
but it also can be used as lightweight Xen control domain (Domain-0).
To implement such fuctionality additional Xen interfaces are needed.
One of them is Xen domain controls (domctls) - it allows to create,
configure and manage Xen domains.

Also, used it as a possibility to update files copyright and licenses
identifiers in touched files.

Signed-off-by: Dmytro Firsov <dmytro_firsov@epam.com>