Support Canon CNIJMediaType printer option

[carlosbuitragosan]

Summary

Some Canon printer drivers expose the media type PPD option as
CNIJMediaType instead of the standard MediaType.

This patch falls back to CNIJMediaType when MediaType is unavailable,
both when enumerating available media types and when submitting print jobs.

This restores paper type selection for printers that expose
CNIJMediaType while preserving the existing behavior for printers that
provide the standard MediaType option.

Tested

• Canon iX6800 series
• macOS

Verified that:

• media types are correctly listed in the print dialog
• the selected media type is passed to CUPS (CNIJMediaType=<value>)
• printing works correctly

[TurboGit]

This does not compile on CI, see:

cups_print.c.o.d -o bin/CMakeFiles/lib_darktable.dir/common/cups_print.c.o -c /__w/darktable/darktable/src/src/common/cups_print.c
/__w/darktable/darktable/src/src/common/cups_print.c: In function 'dt_print_file':
/__w/darktable/darktable/src/src/common/cups_print.c:591:22: error: 'ppd' undeclared (first use in this function)
  591 |     if(ppdFindOption(ppd, "MediaType"))
      |                      ^~~
compilation terminated due to -Wfatal-errors.

@carlosbuitragosan : Can you fix please. TIA.

[carlosbuitragosan]

I’ve fixed the CNIJMediaType handling and pushed the fix in the latest commit. The code now compiles successfully locally.