feat-bug(aria/combobox-listbox): listbox `[multi]="true"` works only for combobox `readonly` true

[silveoj]

Feature Description

If listbox's multi=true and combobox's readonly=false we can select only one item. We can only type first letters of countries. And select only one country. We can't use even standard , separator.

If listbox's multi=true and combobox's readonly=true we can open combobox/listbox and select multiple items.

See live: stackblitz

Use Case

It's useful for multiselect, autocomplete