Add Total VDF Difficulty to Consensus

[jose-blockchain]

Outside of the Finality Window:

• Do NOT use Longest Chain based on number of Blocks.
• Use Longest Chains based on Total VDF Difficulty accumulated.

Otherwise an attacker with a small number of nodes can Mine VDF with a lot of blocks quickly to get a longer chain than the current one.

This feature can be also used later to add Checkpoints or Epoch to compact Daily or Weekly the blockchain.