Check when mismatched sequencing occurs in DataStreamDownload test client reactor

[corbin-phipps]

Is your feature request related to a problem? Please describe.
In TestNetRemoteDataStreamingReactors, the Await function currently checks if the sequence number matches the number of data blocks received. However, it would be helpful to know when exactly that sequence mismatch occurs.

Describe the solution you'd like
Check for sequence mismatch in OnReadDone callback and handle accordingly. Consider either stopping the RPC at the first mismatch, or continuing reads and tracking the number of data blocks dropped/lost.