Multi Url Picker is not updating model

[TheBekker]

Which exact Umbraco version are you using? For example: 8.13.1 - don't just write v8

8.15.1

Bug summary

While creating a custom property editor that uses the "Multi Url Picker", i noticed that it's not updating it's model on the fly.
It only updates when saving/publishing the whole page.

Specifics

MultiUrlPickerController listens for "formSubmitting" event to update $scope.model.value but othervise never updating the model value.

Steps to reproduce

Best way to show:

1. Make properties render out their model.
2. Change value of an Multi Url Picker

Recording.2.mp4

Expected result / actual result

model.value should update, when property is changed.

[nul800sebastiaan]

Fixed in #10957