Fix b/14218193: Support GSA discrete Admin NIC

If a GSA has its discrete admin NIC enabled, it typically has a
separate IP address than the GSA's primary NIC. This change adds
a new optional configuration propery, gsa.admin.hostname, that
allows the adaptor administrator to specify the separate admin
IP address or hostname. If gsa.admin.hostname is not specified,
it defaults to the same value as gsa.hostname.

Code Review:
4 files changed