[PERF]: Cache parquet metadata at the session level

## Problem

`prefetch_parquet_file_metadata_for_ir` fetches parquet footers from S3 at the start of every query execution, even for files that were already read in a previous iteration of the same benchmark or a previous query against the same dataset. The `CachedParquetInfo` objects (which include the parsed `FileMetaData` and pre-built `HybridScanMetadata`, and open kvikio handles as of #23317) are discarded when the query finishes.

From profiling Q1 at SF300 on a g7e.8xlarge:

It takes a second to prefetch the parquet metadata on both iterations. But the second iteration should not pay that cost.

## Proposed Fix

Add a session-level cache of `CachedParquetInfo` objects on the engine. Key the cache on `(path, etag)` where the etag is the S3 object version identifier propagated from polars via #22734.

## Related

- #22667 within-query metadata caching
- #22666 reuse metadata from polars
- #22734 object metadata (size, etag) from polars
- In PR #23317, this would give prefetching workers a larger head start to get the bytes into pinned memory. And therefore should reduce the time producers wait for byte range request futures to resolve.