Create test case to test Dot1Q+L2BD+vhost-user scenario.

High Level Description of the test:

[Top] TG=DUT.

• [Enc]* Eth-dot1q-IPv4-ICMPv4 on TG=DUT and on DUT=VM.
• [Cfg]* On DUT configure two L2BDs (MAC learning enabled); first L2BD with Dot1Q tagged interface to TG-if1 and vhost-user interface to local VM, second one with vhost-user interface to local VM and Dot1Q tagged interface towards TG-if2. Configure linux bridge on VM to pass traffic between both vhost-user interfaces.
• [Ver]* Make TG send ICMPv4 Echo Req tagged with one Dot1q tag from one of its interfaces to another one via DUT and VM; verify that packet is received.
• [Ref] IEEE 802.1q