please provide debug info in Windows builds

The snapshot builds on download.qt.io have no debug info. Multiple times I've had a crash and no way to report it properly. I can't report the crashes without .pdb files. Some of the crashes likely persisted to this day.

The .pdb files could be an option in the snapshot installer, or installed unconditionally. Building Qt Creator on Windows with MSVC is a bit challenging. I'd like them included for Qt libraries and executables.