Summary

Add SbeSingleDocumentLookupExecutor, an SBE-based SingleDocumentLookupExecutor strategy for
local _id point lookups. It compiles a parameterized _id-only SBE plan once and reuses it across
lookups by rebinding the single _id slot, amortizing plan compilation. It is intended for any
caller that issues many _id-style lookups against a fixed namespace: change-stream post-image
(updateLookup) and pre-image lookups, and the internal search idLookup stage.

Details

• SlotBinder rebinds the cached plan's bounds slots per call. Two supported shapes:
  • kIxscanKeyPair – non-clustered id IXSCAN (KeyString low/high slot pair).
  • kClusteredRecordIdPair – clustered collection, min/max RecordId slots (handles scalar and compound BSON _id).
  • Any other plan shape returns kNotHandled so the PrimaryWithFallback chain routes onward.
• The compiled plan is the only cross-call cache; invalidation is keyed on (collectionUUID, CollectionQueryInfo::getPlanCacheInvalidatorVersion()).
• Eligibility runs through LocalLookupEligibility::run(expCtx, nss, documentKey, body); catalog-and-routing errors reset cached state and rethrow so the eligibility's route() retry rebuilds cleanly.
• Plugs into the batched enrichment stage from SERVER-129168.

Testing

Unit tests in sbe_single_document_lookup_executor_test.cpp: functional lookups, cross-call plan reuse (stress, non-clustered + clustered + compound _id), plan-shape assertions (index scan vs bounded clustered scan, no residual filter), and SlotBinder engagement counters.