QUiLoader: there is no normal way to prevent QUiLoader from loading 3rdParty plugins

On creation of QUiLoader object it automatically loads all designer plugins listed in QApplication::libraryPaths(). And there is no way to prevent it from doing so besides altering global property QApplication::libraryPaths itself (which is a quite ugly workaround). Subsequent calls to QUiLoader::clearPluginPaths() won't unload the plugin and its dependencies either.

The more prominent issues arise when a plugin or its dependencies produces some undesireble behaviour upon load. This was a reason for a FreeCAD bug[1].

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Could you please add a normal way to create a QUiLoader object without loading any external plugins besides mending with, i.e add a second constructor with a list of pluginPaths.

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[1]: https://github.com/FreeCAD/FreeCAD/issues/8708