- Added SupportsStatistics helper to check if type supports statistics pushdown
- Created PredicateField struct to hold field resolution information
- Implemented ResolvePredicateFields to extract and resolve field references from predicates
- Currently supports int32 and int64 types
- Skips non-leaf fields and unsupported types
- Handles nested field resolution correctly

Verified:
- Resolves field references using FieldsInExpression
- Uses GetOrcColumnIndex for ORC column mapping
- Handles nested structs by traversing match indices
- Returns comprehensive field information for statistics evaluation

Implemented test to verify ORC metadata caching behavior.

Tests verify that:
1. Metadata is loaded on first scan
2. Subsequent scans reuse cached metadata (read fewer bytes)
3. ClearCachedMetadata() invalidates the cache
4. Scans after cache clear reload metadata

Uses io::TrackedRandomAccessFile to monitor bytes read and verify
that cached metadata reduces I/O on subsequent operations.

The test validates the metadata caching implementation in
OrcFileFragment::EnsureFileMetadataCached(), which lazily loads
and caches ORC file metadata to avoid redundant I/O.

Verified: Metadata caching works correctly, reducing I/O overhead
on repeated scans.

Co-authored-by: Claude Sonnet 4.5 <[email protected]>