Add new CHECKSUM commands

## Why

The Admin interface allows the executing of `CHECKSUM` commands, like `CHECKSUM MYSQL SERVERS`, `CHECKSUM MYSQL USERS`, `CHECKSUM MYSQL QUERY RULES` , etc.
A lot of new tables were introduced, and most of them do not have a `CHECKSUM` command associated with it.
## What
- [ ] identify which `CHECKSUM`s are currently supported
- [ ] add `CHECKSUM` command for all tables
- [ ] document it
