This commit makes it that if the ORPort is set with a single port, it will
bind to both global listen IPv4 and IPv6 addresses.
To pin an "ORPort <PORT>" to be IPv4 or IPv6, the IPv4Only/IPv6Only flags are
honored thus this will _only_ bind on IPv6 for that port value:
ORPort 9050 IPv6Only
Results in: [::]:9050
ORPort 9051 IPv4Only
Results in: [0.0.0.0]:9051
Attempting to configure an explicit IPv4 address with IPv6Only flag is an
error and vice versa.
Closes#33246
Signed-off-by: David Goulet <dgoulet@torproject.org>