Test and fix more combinations for PosixSocketResolve (#4827)

This adds more combinations of parameters for LocalHost and SunnyDay
PosixSocketResolveTest tests, including insuring that lookups work as
expected with address family, socket type, and protocol hints.

This will ensure that PosixSocketResolveTest will also detect systems
where IPv6 localhost lookups don't work.

This also includes various fixes for IPv6 resolve lookups, fixing the
related crashes when used with Starboard 16 in environments with IPv6.

b/369361511
b/377537373