Udp Proxy Fixed Upstream Address Logging In Non Tunneling Path

Fixed the :ref:UDP proxy <config_udp_listener_filters_udp_proxy> not populating the upstream local and remote addresses on the session stream info. As a result the %UPSTREAM_LOCAL_ADDRESS% and %UPSTREAM_REMOTE_ADDRESS% (and their _WITHOUT_PORT / port variants) access log formatters were always empty for non-tunneling UDP -> UDP sessions, unlike TCP proxy. The upstream remote address is now recorded when the upstream host is selected, and the upstream local address once the socket is bound after the first datagram is sent upstream.