fix: evaluate ManifestGroup file filters

[fallintoplace]

Summary

Fixes #663.

This implements ManifestGroup::FilterFiles() instead of accepting the filter as a silent no-op. The change adds a DataFile StructLike wrapper, binds and caches file-level evaluators per partition spec, and applies the evaluator to each manifest entry before returning it.

The reader projection now also includes file-filter referenced metadata columns when callers use Select(...), including widening nested partition references to the full partition struct so partition filters evaluate against the correct positional values.

Tests

• uvx pre-commit run --files src/iceberg/manifest/manifest_group.cc src/iceberg/row/manifest_wrapper.cc src/iceberg/row/manifest_wrapper.h src/iceberg/test/manifest_group_test.cc
• uvx cmake --build build --target manifest_test -j 8
• ./build/src/iceberg/test/manifest_test --gtest_filter='ManifestGroupVersions/ManifestGroupTest.FilterFiles*'
• ./build/src/iceberg/test/manifest_test