ttrpc golang stream request with no FLAG_NO_DATA set

[abel-von]

The empty request is determined by whether FLAG_NO_DATA is set after #208 , but golang ttrpc seems not set this flag even it is an empty request. https://github.com/containerd/ttrpc/blob/main/client.go#L495. Shall we make it compatible with the case that client is golang? or do we set the flag in golang ttrpc?

[wllenyj]

We should be compatible with containerd/ttrpc#157. Or there is a good enough reason to add it in golang.