[FIX] web_kanban: 'create' button
[FIX] web_kanban: 'create' button

This commit fixes two bugs:
  - 'quick_create' is a special value for the on_create option, it is not an
    action xmlid. So when this option is set either in a ungrouped or in an
    empty grouped Kanban view, we should try to execute 'quick_create'.
  - the 'create' button is muted (btn-default instead of btn-primary) in
    grouped Kanban with no column. This status should be updated at each
    do_search, and each time a column is added/deleted.

ygol/odoo,dfang/odoo,dfang/odoo,ygol/odoo,dfang/odoo,hip-odoo/odoo,hip-odoo/odoo,hip-odoo/odoo,hip-odoo/odoo,ygol/odoo,dfang/odoo,hip-odoo/odoo,ygol/odoo,ygol/odoo,dfang/odoo,hip-odoo/odoo,ygol/odoo,dfang/odoo,ygol/odoo