To make the job IPP attributes "print-color-mode", "print-quality",
and "print-content-optimize" actually doing "the right thing" for most
printers we auto-generate PPD option presets now.

CUPS already had the functionality to apply a preset of one or more
PPD option settings for each of the 6 combinations of
"print-color-mode" and "print-quality" settings for longer time but
this was never actually being made use of as it required manually
defining the presets via "APPrinterPreset" PPD attributes. This no one
wants to do with the ~10000 PPDs which come with a typical Linux
distribution nowadays. Even a user with his few print queues does not
want to do it, know how to do it, or know that it is even possible.

This commit makes this fully automatic on every PPD where the presets
are not already manually defined via "APPrinterPreset" attributes.

When creating the PPD cache for a queue's PPD file and the PPD is
without manual presets, it calls the new function
_ppdCacheAssignPresets() which analyses for each PPD option the names
of the choices to find out which choices switch to manochrome or to
color, lower or raise print quality, or improve text/graphics/photo
printing and which are the moset suitable of them. It also analyses
the PostScript/PJL code of the choices to find out whether it affects
the printing resolution.

With this it selects which options get into the the presets and with
which choices.

In addition to presets for the "print-color-mode"/"print-quality"
combos presets for "print-content-optimize" are introduced.

PPD Option settings added by preset are logged on job execution.

This especially revealed that on selecting the final setting for the
color mode/quality presets only 2 of the intended 3 passes were done.

Automatic Windows test build errored on that.

Windows does not have a strcasestr() so we have to provide our own
implementation, as we already did with strcasecmp() and strncasecmp().

… to check for

Checking the PPD file for the HP LaserJet 4050 (PostScript) found more
option/choice names of options which influence print quality:

  - Smoothing
  - Halftone
  - ProRes(600/1200/2400)

Some other of HPLIP's PostScript PPDs use "HPPJLColorAsGray" with
choices "yes" and "no" instead of ""HPColorAsGray" with "True" and
"False".  libcupsfilters: More PPD preset rules, especially for HP

Also analyse choice names for options which contain "Resolution" in
their names.

This way we also cover "cupsColorMode" for example which appears in
auto-generated PPDs for driverless IPP printers (in case we cannot
print directly to the printer but only have access via a CUPS queue).

Also updated a comment and a log message.

…ies record

Static analysis of code, GitHub code scanning, found missing NULL
checks for allocating memory for option choice properties records
(gives NULL when out of memory) and for grabbing the records from a
CUPS array (should now never happen as we now skip the option on the
first memory allocation failure).

Added appropriate NULL checks. Now in case of unsufficient memory the
current option gets skipped on the first failed calloc() call.

Renamed the fields in _ppd_cache_s and updated the comments.