Support inference of the local IP address for Endpoint

[sfackler]

This is a kind of sketchy operation, but it's not all that common to know what your IP is via other means. We basically enumerate all local addresses and look for the first one that "looks right". This can be done with getifaddrs(3) on Unix and GetAdaptersAddresses on Windows.

Brave's logic for reference: https://github.com/openzipkin/brave/blob/c83d32531170de2d9e848026e43d5e2020922ee0/brave/src/main/java/brave/internal/Platform.java#L56