[IMP] web_kanban: hamburger/arrow and item counter icons should be visib...

...le at all times (and not switched on/off on hover)

Task: https://www.odoo.com/web#id=10031&view_type=form&model=project.task&action=327 (this a only a part of this task: web_kanban part in pad)

Pad: https://pad.odoo.com/p/r.4G5Vu8zFmWDa7KXC