Before this commit: When there are no columns in kanban and user is
creating very first column then it will display column + examples
clicking out closes quick create of column and due to which mockup
column also disappeared.
After this commit: Quick create of column will not discard if there
are no columns and user is creating very first column, clicking
outside will discard quick create of column if there is atleast one
column exist.
task-2517684
closesodoo/odoo#70220
Signed-off-by: Simon Genin (ges@odoo) <ges@odoo.com>