[Feature Request] Option to disable deleting items with "Backspace" when using MultiSelect

[SSchulze1989]

Is your feature request related to a problem? Please describe.
When binding to a collection and displaying multiple selections, the default behaviour is to delete the last item when backspace is pressed there is not current search text in the input.

Describe the solution you'd like
While this is obviously an expected behaviour for some, i would like to have an option to disable this deletion to prevent accidental deletes by the user.