This patch adds 'kvm sandbox' which is a wrapper on top of 'kvm run' which
allows the user to easily specify sandboxed command to run in a custom
rootfs guest.

Example usage:

	kvm sandbox -d test_guest -k some_kernel -- do_something_in_guest

Suggested-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>