Move the base types unique to KVM selftests out of kvm_util.h and into a
new header, kvm_util_types.h.  This will allow kvm_util_arch.h, i.e. core
arch headers, to reference common types, e.g. vm_vaddr_t and vm_paddr_t.

No functional change intended.
Reviewed-by: Ackerley Tng <ackerleytng@google.com>
Link: https://lore.kernel.org/r/20240314232637.2538648-3-seanjc@google.comSigned-off-by: Sean Christopherson <seanjc@google.com>