CMake: add version strings to Apple Info.plist files

This fills in the CFBundleVersion and CFBundleShortVersionString fields,
if and when SDL's test-apps are built via CMake.  This is needed to install
the .app bundles on iOS 13+ (using 'xcrun simctl install booted path/to/testsuchandsuch.app')

test/CMakeLists.txt

@@ -145,6 +145,8 @@ if(APPLE)
             if(TARGET_TYPE STREQUAL "EXECUTABLE")
                 set_target_properties("${CURRENT_TARGET}" PROPERTIES
                     MACOSX_BUNDLE_GUI_IDENTIFIER "org.libsdl.${CURRENT_TARGET}"
+                    MACOSX_BUNDLE_BUNDLE_VERSION "${SDL_VERSION}"
+                    MACOSX_BUNDLE_SHORT_VERSION_STRING "${SDL_VERSION}"
                 )
             endif()
         endforeach()