[KIP-146] Unpredictable proposer selection policy

[ian0371]

KIP-146 is a proposal for unpredictable proposer selection policy.
See this PR in markdown
Closes #146

[steve-jeon-KF]

I leave this comment based on today's scrum for other members to be aligned. In KIP-146, the proposer is determined by shuffling without using a Picker and selecting the address at index 0. And to prevent duplicates, the selected proposer is excluded for the next round, and a shuffle is performed for each round.

[hyunsooda]

Minor issue: A function have type signatures, another function does not have. Making align seems look better.

[ian0371]

Changes

• in title, random -> unpredictable
• removed the term "Round robin"
• spec change
  • committee does not change in case of round change
  • proposer is selected from the committee
• add rationale

[kjhman21]

@hyunsooda @jiseongnoh Please approve this one if you guys have no more questions and suggestions.

[hyunsooda]

@ian0371, regarding the recently introduced concept of a fixed committee at round change, is there any underlying rationale or basis for this hypothesis? I have an additional concern regarding the presence of an adversary within the committee, as it seems they could continuously disrupt the consensus if the committee remains fixed until the next block number.

Apologies for the confusion, I'm unsure whether this question should be posted here or as a new issue.