Implements ProcessImplicitRoute and ForwardNewRouteInfoToKnownServers on RouteManager,
and ProcessImplicitGateway on GatewayManager, mirroring Go server/route.go and
server/gateway.go INFO gossip-based peer discovery. Adds ConnectUrls to ServerInfo
and introduces GatewayInfo model. 12 new unit tests in ImplicitDiscoveryTests.
