virnetsocket: Provide socket address format in a more standard form

virnetsocket: Provide socket address format in a more standard form

Our socket address format is in a rather non-standard format and that is
because sasl library requires the IP address and service to be delimited by a
semicolon. The string form is a completely internal matter, however once the
admin interfaces to retrieve client identity information are merged, we should
return the socket address string in a common format, e.g. format defined by
URI rfc-3986, i.e. the IP address and service are delimited by a colon and
in case of an IPv6 address, square brackets are added:

Examples:
    127.0.0.1:1234
    [::1]:1234

This patch changes our default format to the one described above, while adding
separate methods to request the non-standard SASL format using semicolon as a
delimiter.

Signed-off-by: Erik Skultety <eskultet@redhat.com>