HDDS-10338. Implement a Client Datanode API to stream a block

[chungen0126]

What changes were proposed in this pull request?

To reduce round trips between the Client and Datanode for reading a block, we nee a new API to read.

Client -> block(offset, length) -> Datanode
Client <- chunkN <- Datanode
Client <- chunkN+1 <- Datanode
..
Client <-chunkLast <- Datanode

This is using the ability of gRPC to send bidirectional traffic such that the server can pipeline the chunks to the client without waiting for ReadChunk API calls. This also avoids the client from creating multiple Chunk Stream Clients and should simplify the read path on the client side by a bit.

What is the link to the Apache JIRA

https://issues.apache.org/jira/browse/HDDS-10338

How was this patch tested?

There are existed test for reading data.