Test port mac_address update

Adds api admin tests ``test_update_mac`` and ``test_regenerate_mac``.
Also enable the ``port-mac-address-regenerate`` extension in zuul
job.

Related-Bug: #1768690
Depends-On: I7d04beea4810718c3b745de8ea97897b1323267e
Change-Id: I285986c7a19c4804b3c8c3b0a2d2e3f895a46ff7
2 files changed