Move the address:port parsing code to the net helper. Add a default
address option.
Pass the interface address to protocol-simple and use this as the
default address for listening.
This makes sure that when the user passes tcp:3400 that we don't end up
publishing 0.0.0.0:3400 but the actual address of the interface we are
listening on so that the snapcast discover can use this to notify the
snapcast server.
Fixes#4093
Use `getaddrinfo` in `parse_address` instead of `inet_pton`.
Display Ipv6 addresses with scope identifiers correctly in `get_ip`
functions using `if_indextoname`.
