Add translator comments to module names

src/bin/pg_dump/compress_io.c

src/bin/pg_dump/pg_backup_archiver.c

src/bin/pg_dump/pg_backup_custom.c

src/bin/pg_dump/pg_backup_db.c

src/bin/pg_dump/pg_backup_directory.c

src/bin/pg_dump/pg_backup_tar.c

src/bin/pg_dump/pg_dump_sort.c