While looking into a different issue, I've noticed that Visual Studio Intellisense does not work well for Godot project when using Windows Vista+ APIs (e.g. CreateThreadpool), i.e. it does not recognise the APIs because they are defined in Windows header files for Vista+ only.
This is because the WINVER and _WIN32_WINNT symbols don't have their values set in the generated Godot project file. This fixes the problem by setting the values when generating the project file.