Block Production improvement tasks

[alfiedotwtf]

A list of improvements to be done for Block Production:

• Add PoS blockprod functional tests #1004
• Assign Job Key ID when none supplied in produce_block_with_custom_id() #1003
• Prevent node from producing blocks unless connected to N peers #1060
• Prevent staking at the same time with the same key (this should be currently prevented by the job keys)
• Genesis ongoing consensus status is incorrect #1002
• Allow generate_block() to accept Transaction IDs along with encoded signed transactions #756
• Don't stake for previously staked times #1005
• Swap out the handrolled Mempool mock for a mockall implementation #957
• Replace UpgradeVersion with ConsensusUpgrade #992
• Use Builder in more places for blockprod testing #991
• calculate coins from atoms instead of strings full of zeros