Epic: Support bilateral Consensus Node to Block Node Communication

[mhess-swl]

This epic contains the services tasks needed to support and verify communication between a consensus node (CN) and a block node (BN).

For reference, the block node team's equivalent epic can be found here.

Design/Review

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1. Research and verify the overall architecture of the BN simulator
2. Research and verify the block outputs of the BN simulator
3. Research and design a solution for whom a CN should connect to, if its 'primary' BN is unavailable for an extended period of time #15530
   +0
4. Verify behaviors between CN and BN with Block Node team #16316
   +0
5. Design a Block Node Simulator/gRPC Server in process to simulate response codes etc. #16160
   +0
   

Implementation

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1. Implement GRPC streaming of blocks from the consensus node #15540
   Block Streams +1
2. Update BlockStreamManagerImpl to support a local cache of Blocks to be resent to a BN #16162
   +0
3. Implement an initial selection process for the Consensus Node to pick a Block Node (pick at random) #16163
   +0
4. Implement logic to retry connecting to a Block Node and then possbily pick another Block Node #16164
   +0
5. Update GrpcBlockItemWriter writeItem and writeItems methods to account for new protobuf definition #16165
   +0
6. Implement functionality in GrpcBlockItemWriter to allow sending of EndOfStream status codes #16157
   +0
7. Implement functionality in GrpcBlockItemWriter for acting on PublishStreamResponseCodes (from BN) #16158
   +0

Testing

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1. Write a test plan for the Consensus Node to Block Node Communication
2. Write test cases for an initial set of known edge cases
3. (If needed) Support the block node team in setting up an integration environment for testing CN <-> BN communication