Feat/1207513338125664 delayed staking rewards

[talhadaar]

WIP - Opened for discussion

• CollatorBlock: now a double map, stores numbers of blocks authored by a collator in each session.
• AtStake StorageDoubleMap: here we snapshot collator staking state at the start of the round.
• DelayedPayoutInfo: Stores the info we need to calculate payouts for collators/delegators for blocks generated in previous session.
• payout_collator(end_session_flag) - Takes a block author from previous session from CollatorBlock, takes their staking state of previous session from AtStake, calculates and pays out their rewards based DelayedPayoutInfo.
  • end_session_flag indicates if this round is ending(probably by force_new_roud), if so, then execute all remaining delayed payouts for the previous round.
  • if this flag is true, then snapshot of previous round is also cleared from storage.

---

• To see the specific tasks where the Asana app for GitHub is being used, see below:
  • https://app.asana.com/0/0/1207513338125664