move kvm executable/script from qemu-kvm to qemu-system-foo, make it...

move kvm executable/script from qemu-kvm to qemu-system-foo, make it multi-arch, and remove qemu-kvm package

This removes qemu-kvm old/compat package and creates /usr/bin/kvm
executable - which is actually a link to native-arch qemu-system-foo
executable, and create this link not only for x86 but for other
architectures too. Update kvm.1 manpage.

While at it, refresh and deprecate Ubuntu's kvm-spice executables
from old package, make them print a warinig to use qemu-system-x86_64
directly