qml: Fix visualFocus on navigation

This MR fixes the visualFocus (the thin rectangle) while navigating the video, music and browse views with the keyboard. Enforcing that items are selected properly while retaining the visualFocus information when loading or reloading a page. Although that's fairly uncommon behavior on QML projects it effectively enables us to use VLC as a media center with left, right, top, bottom and a back button.

depends !3805 (merged)