macOS: Support printing when no printers are installed

Even if there are no printers installed, we can still show the print
dialog, which gives the user feedback about no printers being installed,
allows them to install one, or allows them to print to PDF as a
fallback.

The code for printing to PDF has been re-enabled, and the conditions
of QTBUG-38820 have been removed as the problem is no longer present.
The code also takes into account the possibility that the user chose
to print to PostScript, which we don't yet support, but warn about.

We now also support opening the printed document in Preview. This
requires a minor assumption about the print operation being done
synchronously after the print dialog is accepted, but this is
something we can improve in the future with internal APIs if it
turns out to be a problem.

Printing workflows such as sending the printed document via mail
or messenger are not not supported, and will give a warning.

Fixes: QTBUG-36112
Change-Id: I8ba9e2c5ce31a5a06542c4a7126d005e4b27f2be
Reviewed-by: Andy Shaw <andy.shaw@qt.io>

0 files changed, 0 insertions, 0 deletions