RESPONDER: Add sss_dp_resolver_get_send
    
    This function sends requests for IP hosts and networks to the resolver
    target. Will be used by following cache req plugins:
    * cache_req_ip_host_by_name
    * cache_req_ip_host_by_addr
    * cache_req_ip_network_by_name
    * cache_req_ip_network_by_addr
    
    Signed-off-by: Samuel Cabrero <scabrero@suse.de>
    
    Reviewed-by: Sumit Bose <sbose@redhat.com>