Transfer 400s in seqret service through new sequence reporter to client w/400

[ryanrdoherty]

The SequenceReporter reporter calls out to the sequence retrieval (containerized) service to do work and then streams its response back to the client. We do our best to send the correct request input to the service but it can still throw 400 if the request results in >SOME_MAX # of sequences (which the reporter cannot know in advance). In that case, we want to pass the 400 status and the message back to the WDK client, but still throw 500 if we either cannot successfully reach seqret service or if the service fails.