qml: Use 'var' for properties altered by StackView.replace()
When calling StackView.replace() together with custom properties we have to provide generic types (var, int, string). Otherwise we get 'casting' issues when using a specific one (like MLItemId). This was causing invalid values to be restored when navigating between the QML MediaLibrary views.
fix #26629 (closed)
Edited by Benjamin Arnaud