CMake: Make qt_add_executable more minimalistic

As per the public API review, we want qt_add_executable to be a
minimal shim around CMake's add_executable with as little Qt specific
behavior as it makes sense.

This means:
- not setting the WIN32 and MACOSX_BUNDLE
- not linking against Gui, only Core
- not generating a windows RC file

Users should handle those particularities themselves, ensuring that
qt_add_executable can be used by a bigger audience.

Fixes: QTBUG-87664
Task-number: QTBUG-86827
Change-Id: Ib424dd95266352eb035a344ca03b6b81e47bd9e8
Reviewed-by: David Faure <david.faure@kdab.com>
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>

src/corelib/Qt6CoreMacros.cmake

@@ -439,16 +439,9 @@ function(qt6_add_executable target)
         set_property(TARGET "${target}" PROPERTY OBJCXX_VISIBILITY_PRESET default)
         qt6_android_apply_arch_suffix("${target}")
     else()
-        add_executable("${target}" WIN32 MACOSX_BUNDLE ${ARGN})
+        add_executable("${target}" ${ARGN})
     endif()
     target_link_libraries("${target}" PRIVATE Qt::Core)
-    if(TARGET Qt::Gui)
-        target_link_libraries("${target}" PRIVATE Qt::Gui)
-    endif()
-
-    if (WIN32)
-        _qt_internal_generate_win32_rc_file(${target})
-    endif()
 
     if(ANDROID)
         qt_android_generate_deployment_settings("${target}")