MultiSelectComboBox: allow sorting selected items by value

[ddanewitz]

Describe your motivation

The current MultiSelectComboBox has no possibility to sort the selected items by value. Instead they are sorted by selection time. Gatanaso's MultiSelectComboBox had a simple Method that would do the sorting by value.

Describe the solution you'd like

Provide a method for the MultiSelectComboBox to sort selected items by their value.

Describe alternatives you've considered

No response

Additional context

No response

[web-padawan]

Thanks for the issue. Just to clarify, the original add-on has ordered property and related logic to sort items.