test: create all iftypes, verify in operational

[troglobit]

A new test to verify that all interface types can be created (no traffic) and read out from the operational datastore:

• [ ] One standalone Ethernet/Etherlike port, e1
• [ ] One loopback interface, lo
• [ ] One empty bridge, br0
• [ ] One Ethernet/Etherlike port, e2, set as a bridge port in br1
• [ ] A VETH pair, veth0a <--> veth0b, where veth0b is a bridge port in br1
• [ ] VLAN interfaces:
  • [ ] VLAN interface on top of Ethernet/Etherlike with VLAN 10 and 30, e3.10 and e4.30
  • [ ] VLAN interface on top of a bridge, br2.40
  • [ ] VLAN interface on top of VETH interface with VLAN 20, veth0a.20 as bridge port in br2
  • [ ] VLAN interface as bridge port, e4.30 as bridge port in br2

Verify by reading out operational datastore, check that each interface name exists with the correct type.

Regression test for:

• 618

[axkar]

After further discussion, it was decided that the entire test model (topology) should be revised according to the following ASCII diagram:

 lo     br-0                    br-Q.40           br-D         br-X
  |       |                       |                |            |
  o       o      eth-Q.10       br-Q           veth0a.20     eth-X.30
                         \     /    \              |            |
                          eth-Q     veth0b       veth0a        eth-X
                                         `---------'