Focus policy

[plfiorini]

Shell surface items only have the "click to focus" policy but we need more, like "focus follows mouse". We also want an automatic mode that will allow the compositor to choose: lock screens will need that, in order for the surface layout to automatically give them focus.

[plfiorini]

Actually, now that I remember: I had implemented this in WaylandShell but it only has automatic and manual policies. Guess that manual could be expanded into more detailed policies such as those mentioned above (click to focus and focus follows mouse).

Create a QQuickItem::FocusPolicy enum with ClickToFocus and FocusFollowsMouse instead of the focusOnClick property.