Generate hash of DVM and EVM DBs

[Bushstar]

Summary

• Generates a hash of the DVM and EVM DBs to be used to compare nodes to check integrity.

Implications

• Storage

  • [ ] Database reindex required
  • [ ] Database reindex optional
  • [ ] Database reindex not required
  • [x] None

• Consensus

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

[prasannavl]

Merging this for now. But let's add the EVM, and Ocean DB indexes in retrospectively, so the single API can generate complete integrity checks.