Cooldown changes

[td202]

Purpose

Closes #1142 #1145 #1146 #1147 #1148 #1176 #1177

Implement cooldown changes in the node.

Changes

• Split getPassiveDelegationStatus out of getPoolStatus so that the execution paths for getPoolInfoV2 and getPassiveDelegationInfoV2 are disentangled.
• Update account hashing to include the cooldown queue.
• Update the account structure to include the cooldown queue.
• Revise the computation of account available amounts (it is now protocol-version specific).
• Epoch transition handling:
  • bsoProcessPendingChanges is only available before P7 (versions that do not support flexible cooldown).
  • bsoProcessCooldowns removes cooldowns that have expired and then moves pre-cooldowns into cooldown.
  • bsoProcessPrePreCooldowns moves pre-pre-cooldowns into pre-cooldown.
  • Change payday handling so to call bsoProcessCooldowns instead of bsoProcessPendingChanges from P7 (via paydayHandleCooldowns)
  • On snapshot epoch, pending changes are no longer accounted for (from P7) when snapshotting since they will always be NoChange. Instead bsoProcessPrePreCooldowns is called.
  • The NewReleaseSchedule structure is reused to track cooldown expiries.
  • ...

Checklist

• My code follows the style of this project.
• The code compiles without warnings.
• I have performed a self-review of the changes.
• I have documented my code, in particular the intent of the
  hard-to-understand areas.
• (If necessary) I have updated the CHANGELOG.