Convert newlines to spaces in names written in v11+ pg_dump comments.

Convert newlines to spaces in names written in v11+ pg_dump comments.

Maliciously-crafted object names could achieve SQL injection during
restore.  CVE-2012-0868 fixed this class of problem at the time, but
later work reintroduced three cases.  Commit
bc8cd50fefd369b217f80078585c486505aafb62 (back-patched to v11+ in
2023-05 releases) introduced the pg_dump case.  Commit
6cbdbd9e8d8f2986fde44f2431ed8d0c8fce7f5d (v12+) introduced the two
pg_dumpall cases.  Move sanitize_line(), unchanged, to dumputils.c so
pg_dumpall has access to it in all supported versions.  Back-patch to
v13 (all supported versions).

Reviewed-by: Robert Haas <robertmhaas@gmail.com>
Reviewed-by: Nathan Bossart <nathandbossart@gmail.com>
Backpatch-through: 13
Security: CVE-2025-8715