Move the definition of "struct kvm_queued_exception" out of kvm_vcpu_arch
in anticipation of adding a second instance in kvm_vcpu_arch to handle
exceptions that occur when vectoring an injected exception and are
morphed to VM-Exit instead of leading to #DF.

Opportunistically take advantage of the churn to rename "nr" to "vector".

No functional change intended.
Signed-off-by: NSean Christopherson <seanjc@google.com>
Reviewed-by: NMaxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20220830231614.3580124-15-seanjc@google.comSigned-off-by: NPaolo Bonzini <pbonzini@redhat.com>