Mining: Toggle ascending via Gov var

[Bushstar]

Summary

• Miner should mint blocks in ascending order based on Governance vars, not fork height. Reesolves -ascendingstaketime should be enforced when v0/params/feature/ascending_block_time is active #3040.

Implications

• Storage

  • Database reindex required
  • Database reindex optional
  • Database reindex not required
  • None

• Consensus

  • Network upgrade required
  • Includes backward compatible changes
  • Includes consensus workarounds
  • Includes consensus refactors
  • None