feat(rust): implement idempotency-aware retry logic [PECOBLR-2091]

Implements the standardized DBSQL connector retry specification with:

- RequestType enum as single source of truth for request classification
- Idempotent vs non-idempotent retry strategies with distinct behavior
- Exponential backoff with random jitter (50-750ms)
- Retry-After header support (seconds and HTTP-date formats)
- Cumulative overall timeout (default 900s)
- Per-category retry config (SEA, CloudFetch, Auth) with global defaults
- Structured DEBUG logging per attempt and per request summary
- Metadata queries (list_*) classified as idempotent via ExecuteMetadataQuery

Co-authored-by: Isaac

Author: vikrantpuppala

rust/Cargo.lock

@@ -53,6 +53,9 @@ chrono = { version = "0.4", features = ["serde"] }
 # LZ4 decompression for CloudFetch
 lz4_flex = "0.11"
 
+# Random number generation (retry jitter)
+rand = "0.9"
+
 # Concurrent data structures
 dashmap = "5"