storage: add basic mz-rocksdb crate

[guswynn]

This pr is in-service of #17067.

It adds a mz-rocksdb crate, derived from this benchmark: https://github.com/MaterializeInc/materialize/blob/main/src/storage/examples/upsert_open_loop.rs, and unit tests it. It is async (so it is easy to integrate into timely dataflows, and runs the rocksdb instance

@danhhz for the metrics, I opted for adding some rocksdb specific ones (latencies of gets and writes), and will get other metrics (like e2e latency for a full batch upsert) using the trait method we discussed, in later pr's. Let me know if you spot any other metrics that make sense!

Motivation

• This PR adds a known-desirable feature.

Tips for reviewer

Some amount of complexity here is due to graceful shutdown being required by rocksdb: rust-rocksdb/rust-rocksdb#767

Unfortunately, it seems as rocksdb is determined to segfault in scenarios we wont be able to gracefully shutdown from.

Note also that rocksdb errors (like io errors) are considered permanently fatal, and in the future, will cause sources to restart

Checklist

• This PR has adequate test coverage / QA involvement has been duly considered.
• This PR has an associated up-to-date design doc, is a design doc (template), or is sufficiently small to not require a design.
  https://www.notion.so/materialize/Spill-to-disk-for-UPSERT-a9bbe06e80374528a259635488a544cd?d=19b4ad2d39394f039ccdc355c848d7a0
• This PR evolves an existing $T ⇔ Proto$T mapping (possibly in a backwards-incompatible way) and therefore is tagged with a T-proto label.
• If this PR will require changes to cloud orchestration, there is a companion cloud PR to account for those changes that is tagged with the release-blocker label (example).
• This PR includes the following user-facing behavior changes:

[aljoscha]

Looks very good! Modulo some stray comments/copy-paste errors, and some minor restructuring of, say, tests.

Did you try slotting this into the upsert open-loop benchmark?

[danhhz]

overall looks good! i'll leave the stamp to aljoscha. definitely include me when you PR the pluggable trait for this, please

[philip-stoev]

Not sure what is there for me to test here, but please do add me to any PR that implements the actual spill to disk!