This commit adds the ability to select multiple values from the
SelectMenu component. A list of tags are displayed in the toggler
to remove already selected values, and selected values are colored
in the list of choices.
This feature is similar to how jquery select2 handles multiple
selections, by adding the values in the input toggler. The feature
will be used by the studio sidebar during the refactor.
Part-of: odoo/odoo#115799
luvi
2d28239f9b