Stop multiplexing virNetClientSend for two different purposes,
instead add virNetClientSendWithReply and virNetClientSendNoReply

* src/rpc/virnetclient.c, src/rpc/virnetclient.h: Replace
  virNetClientSend with virNetClientSendWithReply and
  virNetClientSendNoReply
* src/rpc/virnetclientprogram.c, src/rpc/virnetclientstream.c:
  Update for new API names