Host tools fail when cross-compiling for Windows ARM

This issue occurs on an x86_64 machine when trying to compile a project for arm64.

To reproduce:

1. Create a new project in Visual Studio using one of the standard Qt templates (such as a widgets app)
2. Select an ARM kit
3. Build. This results in errors like "Error starting process C:/Qt6/6.7.0/msvc2019_arm64/bin/uic: The system cannot find the file specified"