Add equality-delete apply on PyArrow reads

[daviddallakyan2005]

Closes #3270

Rationale for this change

Index equality delete files and apply them on PyArrow scans so CDC and merge-on-read tables can be read. Equality deletes still cannot be written.

This ports the DeleteFileIndex work from #3285 onto current main, skips bounds prune when an equality field has been dropped, and left anti joins matching equality delete rows after positional deletes. It supersedes #3285, which is open and conflicting. Credit to Alex Stephen for the index. Please close #3285 if this path is preferred.

When a data file has equality deletes, the scan concatenates that file’s record batches, aligns each matching equality-delete table by field id then concats, adds is_null / fill_null (and is_nan for floats) helper columns per key, left anti joins once, then yields the survivors; files with only position deletes still yield each scanner batch.

Are these changes tested?

Yes. Merged main after #3804 so integration-test is not stopped by the deprecated PuffinFile.to_vector() call.

make test
3962 passed, 3 skipped, 1570 deselected

make test-integration PYTEST_ARGS="-v -k test_read_spark_written_puffin_dv"
1 passed, 5534 deselected

Are there any user-facing changes?

Yes. Tables that already store equality deletes can be scanned.