Aptos governance (votes and proposal creation) schema and validation

Staking pool balances as extracted from changes logs ( i.e. `aptos.core.fact_changes`) when an individual makes a staking action. To calculate balance at a point in time, isolate a single record for each pool. This table is transactional-based, so balances are updated with every staking event by users. Note - the amount in balance is decimal adjusted by 10^8.