PieceDirectory initial implementation

[nonsense]

This PR is heavy WIP. We cannot merge and release this work, before we have very high confidence on the future data model for the PieceDirectory as well as its performance, alongside migrations from current boost to it.

It must:

• ✅ produce data model for PieceDirectory for both implementations (based loosely on https://docs.google.com/document/d/15ziYCc56q8xsr9P1nfj7dbpDZ5h_ZZWGYxH93RiLgyM/edit)
• ✅ add migrations to get from DAGStore and PIeceStore to PieceDirectory within boostd-data
• ✅ performance benchmarks for the PieceDirectory with boost running LevelDB and YugabyteDB backend for small-, mid- and large- size validators (tbd concretely how many GiB worth of deals these entail) ; Benchmarks / Scaling requirements analysis for boostd-data state service and PieceDirectory #615

LID benchmarking doc -- https://docs.google.com/document/d/1s63C9n1xKWLitkGGKgFfQXY8tmDbmgcd0-tfxW-BZmw/edit#heading=h.nuq3vzhs6roi
LID benchmarking PR -- #1276

agenda:
✅ - done
🚧 - in-progress
❌ - not started

---

TODO:

• make sure that boostd-data and boost are not dependent on each other.

[LaurenSpiegel]

This PR is heavy WIP. We cannot merge and release this work, before we have very high confidence on the future data model for the PieceMeta store as well as its performance, alongside migrations from current boost to it.

It must:

• 🚧 produce data model for Store for both implementations (based loosely on https://docs.google.com/document/d/15ziYCc56q8xsr9P1nfj7dbpDZ5h_ZZWGYxH93RiLgyM/edit)
• ❌ add migrations to get from DAGStore and PIeceStore to PieceMeta within boostd-data
• ❌ performance benchmarks for the PieceMeta and Store with boost running LevelDB and Couchbase backend for small-, mid- and large- size validators (tbd concretely how many GiB worth of deals these entail) ; Benchmarks / Scaling requirements analysis for boostd-data state service and PieceMeta #615

agenda: 🚧 - in-progress ❌ - not started

1. What is the difference between Store and PieceMeta?
2. Where did the requirement to support both leveldb and couchbase come from?

[nonsense]

merged into release/v2 (which was branched out of main)