[FIX] web: kanban: global click and 'image' widget

Let's assume a kanban view with oe_kanban_global_click className
(i.e. clicks on the card open the record in a form view), and an
image with the 'image' widget. This is for instance the case of the
hr.employee kanban view.

Before this rev., clicking on the image didn't open the record in
form view.