Enable directional / spatial focus navigation in QGraphicsView and QML

Background

On platforms that do not provide support for mouse or touch interaction, focus between input fields needs to be moved using e.g. arrow keys. To support this, tab order to move focus between widgets is not enough - and a more flexible approach is needed. E.g. using the arrow keys could be a property to enable on input widgets - where the developer would need to define the next focusable item for left, right, up, down keys.

Use-cases

Enable navigating a set of line-edits that are positioned in a grid rather than a flat list, where using up/down is not sufficient to navigate between the input.