Make sure qoffscreen.dll is included in distribution

Headless plot export requires qoffscreen.dll, make sure this file is included in installer.

ApplicationExeCode/CMakeLists.txt

@@ -568,6 +568,14 @@ if(RESINSIGHT_PRIVATE_INSTALL)
       install(DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/windeployqt/"
               DESTINATION ${RESINSIGHT_INSTALL_FOLDER}
       )
+
+      # install additional DLLS not able to be found by windeployqt
+      set(qt5_offscreen_name "$<IF:$<CONFIG:Debug>,qoffscreend,qoffscreen>")
+      install(
+              FILES ${qt5_install_prefix}/plugins/platforms/${qt5_offscreen_name}.dll 
+              DESTINATION ${RESINSIGHT_INSTALL_FOLDER}/platforms
+    )
+
     endif()
 
     # install GRPC-related DLLs and generated_classes.py