Expose Iceberg position delete records via metadata table

To debug issues with position delete files, or detect table corruption we could expose the delete records via the metadata table syntax, e.g.:

SELECT INPUT__FILE__NAME, file_path, pos
FROM db.ice_t.position_delete_records;

Adding virtual column INPUT_FILE_NAME is useful because it can tell which delete file contains the records.

We should re-use IcebergPositionDeleteTable for this: https://github.com/apache/impala/blob/master/fe/src/main/java/org/apache/impala/catalog/IcebergPositionDeleteTable.java