fix: Combobox VoiceOver announcement not respecting `aria-label` of `ListBoxItem` (#8908)
* add ComboBox Story for ListBoxItem with aria-label
This can be used to check whether the screen-reader announcement for option selections reads the correct label for each option, especially on mac, where there is a special codepath for this.
* fix `CollectionBuilder` to handle `aria-label` correctly
This commit ensures the aria-label prop from the ListItem is read into the corresponding attribute ElementNode
* only add key if it exists
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Co-authored-by: Robert Snow <rsnow@adobe.com>
Co-authored-by: Robert Snow <snowystinger@gmail.com>