net/dot1ag-utils: new port

dot1ag-utils is a 2-clause BSD licensed suite of utilities providing Layer 2
Ping & Traceroute functionality for *BSD platforms. The code is currently
hosted at SourceHut ; please be considerate with "git archive" load. This
had languished in Bugzilla for some 15 years after thompsa@ submitted it.

Approved-by: pi
PR: 163072