Add the ability to support VLAN tags for Open vSwitch virtual port
types. To accomplish this, modify virNetDevOpenvswitchAddPort and
virNetDevTapCreateInBridgePort to take a virNetDevVlanPtr
argument. When adding the port to the OVS bridge, setup either a
single VLAN or a trunk port based on the configuration from the
virNetDevVlanPtr.
Signed-off-by: NKyle Mestery <kmestery@cisco.com>