[1.0.2] Test regression of syncing and replay with actual committed reference blockchain data

[linh2931]

To be confident that changes do not unintentionally introduce changes of the consensus protocol, we would like to add a testing utility that generates reference blockchain data and a new test that checks for regression in compatibility of syncing and replaying the reference blockchain data.

The PR

• provides a command line option --save-blockchain to generate and save the reference blockchain data to unittests/test-data/consensus_blockchain directory. The full command is unittests/unit_test -t savanna_misc_tests/verify_block_compatibitity -- --save-blockchain.
• loads the reference blockchain into a nodeos by replaying it, and and verifies the block ID of the replayed LIB matches with the ID of LIB in the reference blocks log.
• starts another nodeos instance from reference snapshot, sync blocks from the replayed nodeos, and verifies resulting block ID.

Resolves #742

[ericpassmore]

Note:start
category: Tests
component: Internal
summary: Enhance test framework and test cases to sync and replay using actual committed reference blockchain data.
Note:end