sysutils/py-saltext.freebsd: new port

This is a Salt extension for interacting with various FreeBSD-specific
commands. The bsd.shadow module, used by all BSDs, is also included.
The modules herein used to be part of Salt, in version 3006, but are now
developed in a separate repository.

PR: 296290
Reviewed by: krion
Approved by: krion (ports)
Sponsored by: ConnectWise