Change PacProxySelector to return unresolved addr

This was found by a bug in Firefox where it expects the addresses from a
ProxySelector to be unresolved.  Since ProxySelectorImpl returns unresolved
addresses the PAC version should as well to avoid breaking apps.

The ProxyServer also needed to be updated to reflect this change as it was
expecting a resolved InetSocketAddress.

Bug: 11443853
Change-Id: I3a4e9e248d22d7808603c147660df708e01cdf82