## Description 

Add two `Store` implementations:
- RocksDBStore as the real persistent store.
- MemStore for testing.

`DagState` will be implemented in the next PR.

A few changes from https://github.com/MystenLabs/sui/pull/15630 and
https://github.com/MystenLabs/sui/pull/15684 are pulled into this PR.

## Test Plan 

Unit tests.

---
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### Type of Change (Check all that apply)

- [ ] protocol change
- [ ] user-visible impact
- [ ] breaking change for a client SDKs
- [ ] breaking change for FNs (FN binary must upgrade)
- [ ] breaking change for validators or node operators (must upgrade
binaries)
- [ ] breaking change for on-chain data layout
- [ ] necessitate either a data wipe or data migration

### Release notes