Instantiating `QWebEngineProfile` creates an empty data directory

`QWebEngineProfile` provides methods to set data/cache/... paths, such as `
setPersistentStoragePath(...)`. However, just instantiating `QWebEngineProfile` with a profile name creates an empty directory in the default data path (e.g. `%APPDATA%\<AppName>\QtWebEngine\<ProfileName>`), due to the following call chain:

• https://github.com/qt/qtwebengine/blob/dev/src/core/api/qwebengineprofile.cpp#L330
• https://github.com/qt/qtwebengine/blob/dev/src/core/profile_adapter.cpp#L74
• https://github.com/qt/qtwebengine/blob/dev/src/core/profile_qt.cpp#L59
• https://github.com/qt/qtwebengine/blob/dev/src/core/profile_qt.cpp#L234
• https://github.com/qt/qtwebengine/blob/dev/src/core/pref_service_adapter.cpp#L69
• https://github.com/qt/qtwebengine/blob/dev/src/core/profile_adapter.cpp#L150

This is problematic especially for portable apps, which want to redirect all data files to a portable directory. I would prefer if the directory was created on-demand, instead of during the class initialization.