Stop updating AutoSuggestBox on selection (#17961)
`AutoSuggestBox` has a `SuggestionChosen` event and any reasonable
person would assume that this means one of the items was chosen.
But with WinUI it's raised whenever a suggestion is merely highlighted.
`QuerySubmitted` is the right event instead. Clearly that naming is
a lot better than `SuggestionChosen`, since the property to get the
chosen item is called `ChosenSuggestion`.
WinUI, like the unrelenting wilderness of a world indifferent to human
suffering, stands as a testament to the futility of human aspiration.
Closes #17916
## Validation Steps Performed
* Type "Casc"
* Move up/down with the arrow keys
* Neither the filtered list nor the text updates ✅
* Press Enter on an item
* Text updates ✅
