Required schema for the MVP version

[clearloop]

1. General

1.1 block header

already exist in the current code, need to add more useful fields, will be used for the block history section, e.g. latest block in etherscan.io

1.2 the latest statistic

see migrate_service for how to getting this value, which uses storage key STATISTICS in the raw db

2. Advanced

2.1 service account data

similar to statistics , but need to extract from the hook, see the implementation of on_service_xxx

2.2 chain state snapshot (example)

we might not need this atm

there is a method in the Storage trait can extract it automatically