Add LSApplicationCategoryType to OSX export template

[DrMoriarty]

Godot version

3.3.2.stable

System information

MacOSX 10.15.7 (19H2)

Issue description

When I try to upload exported game to Apple AppStore for Mac I have this error:

ERROR ITMS-90242: "The product archive is invalid. The Info.plist must contain a LSApplicationCategoryType key, whose value is the UTI for a valid category. For more details, see "Submitting your Mac apps to the App Store"."

It seems that LSApplicationCategoryType should be in misc/dist/osx_template.app/Contents/Info.plist. Valid values described at https://developer.apple.com/documentation/bundleresources/information_property_list/lsapplicationcategorytype?language=objc
I think that it will be enough to add default value public.app-category.games. But it will be much better if user could customize it to any game subcategory.

Steps to reproduce

Try to publish a game to Mac AppStore.

Minimal reproduction project

No response