xwayland: always offer focus in Globally Active case

xwayland: always offer focus in Globally Active case

In 9e3785f8cd7a, a heuristic was added to assume that NORMAL and DIALOG
window types were always focusable. (This was before we had the "offer
focus" mechanism in place.)

However, we should still call wlr_xwayland_surface_offer_focus() for
these views, in case they actually don't want focus. (This is uncommon
but has recently been seen with WeChat popups, which have both NORMAL
and UTILITY type.)

To make this possible, refine view_wants_focus() to return either
LIKELY or UNLIKELY for Globally Active input windows. This decouples
the question of "should we try to focus this view" from the actual
mechanism used to do so.