EPIC: Consensus-to-Block node integration

[jsync-swirlds]

This epic consists of designing, testing, and verifying the integration between consensus node and block node when a consensus node is publishing a block stream to a block node.

Block Node Tasks

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1. Design handshake between CN and BN to determine what Block to start streaming from. #120
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2. Implement Connection from CN to BN. (TBD Details on how to select a BN)
3. Establish an integration environment (single server?) for testing
4. Add support to Block Node for a "missed block" response (CN sends block later than next)
5. Add support to Block Node for an "old block" response (CN sends block already present)
6. Add support to Block Node for error responses (BN encounters an unrecoverable internal error).
7. Add support to Block Node for "behind" response (BN is behind CN and needs to catch up).

Block Stream Simulator Tasks

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1. Add support to the Block Stream Simulator to send out-of-order blocks
2. Add support to the Block Stream Simulator to fail sending mid-block
3. Add support to the Block Stream Simulator to handle BN error response(s).
4. Add support to the Block Stream Simulator to test Block Node "behind".

Consensus Node services team will track associated work on consensus node in a mirror epic.