Add lpoptions support and destination/job improvements

[Abd002]

1. fix(destination): free the options cupsCopyDestInfo actually allocated

get_detailed_info and is_option_supported freed the options pointer they
built before calling cupsCopyDestInfo, but that call can reallocate the
options array internally. Free what the struct points to afterward instead.

2. feat(destination): read and write default and per-destination lpoptions

Adds Destinations::named_destination, default_destination_name,
set_destination_option, and clear_default_destination. The default-name
lookup follows libcups' own precedence ($LPDEST/$PRINTER, user lpoptions,
system lpoptions, scheduler default) via cupsGetNamedDest rather than
reading files directly, so it stays correct on a machine with different CUPS
directories.

3. refactor(job): keep a job's own destination instead of re-resolving it by name

Job now owns the Destination it was created from instead of storing its
name and re-resolving it on every operation. This also removes a separate
is_accepting_jobs() pre-check that raced against the real state — CUPS's
own server-error-not-accepting-jobs response is now mapped to
Error::PrinterNotAccepting directly.