Infer legacy network type for ConnectivityManager.requestNetwork

ConnectivityManager.requestNetwork pass TYPE_NONE to
sendRequestForNetwork which prevents it from being used with legacy API
requestRouteToHostAddress. This CL infers the legacy network type
automatically from the network capabilities.

b/16324360

Change-Id: I591d38f875f42f56e8cfc157db2069c9eee0ee26