ui/cocoa: Remove allowedFileTypes restriction in SavePanel

ui/cocoa: Remove allowedFileTypes restriction in SavePanel

setAllowedFileTypes is deprecated in macOS 12.

Per Akihiko Odaki [*]:

  An image file, which is being chosen by the panel, can be a
  raw file and have a variety of file extensions and many are not
  covered by the provided list (e.g. "udf"). Other platforms like
  GTK can provide an option to open a file with an extension not
  listed, but Cocoa can't. It forces the user to rename the file
  to give an extension in the list. Moreover, Cocoa does not tell
  which extensions are in the list so the user needs to read the
  source code, which is pretty bad.

Since this code is harming the usability rather than improving it,
simply remove the [NSSavePanel allowedFileTypes:] call, fixing:

  [2789/6622] Compiling Objective-C object libcommon.fa.p/ui_cocoa.m.o
  ui/cocoa.m:1411:16: error: 'setAllowedFileTypes:' is deprecated: first deprecated in macOS 12.0 - Use -allowedContentTypes instead [-Werror,-Wdeprecated-declarations]
      [openPanel setAllowedFileTypes: supportedImageFileTypes];
                 ^
  /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Frameworks/AppKit.framework/Headers/NSSavePanel.h:215:49: note: property 'allowedFileTypes' is declared deprecated here
  @property (nullable, copy) NSArray<NSString *> *allowedFileTypes API_DEPRECATED("Use -allowedContentTypes instead", macos(10.3,12.0));
                                                  ^
  /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Frameworks/AppKit.framework/Headers/NSSavePanel.h:215:49: note: 'setAllowedFileTypes:' has been explicitly marked deprecated here
  FAILED: libcommon.fa.p/ui_cocoa.m.o

[*] https://lore.kernel.org/qemu-devel/4dde2e66-63cb-4390-9538-c032310db3e3@gmail.com/

Suggested-by: Akihiko Odaki <akihiko.odaki@gmail.com>
Reviewed-by: Roman Bolshakov <r.bolshakov@yadro.com>
Tested-by: Roman Bolshakov <r.bolshakov@yadro.com>
Reviewed-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20220215080307.69550-11-f4bug@amsat.org
Reviewed by: Cameron Esfahani <dirty@apple.com>
Reviewed-by: Akihiko Odaki <akihiko.odaki@gmail.com>
Tested-by: Akihiko Odaki <akihiko.odaki@gmail.com>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>