Label group - live region/a way to convey a label was added

Is this a new component or an extension of an existing one?
Label group

Describe the feature
Currently when a label is added via the examples/demos where a label can be added, there's no indication that a label was successfully added when interacting via VoiceOver.

A live region on the label group when addLabelControl is passed in would help resolve this, but may be verbose if there are a lot of labels (each label would get read out loud, not just the newly created one).

Are there visuals for this feature? If applicable, please include examples for each state and for varying widths
Include screenshots or links to Marvel or other mockups.
N/A

Any other information?
N/A

Jira Issue: PF-170

Label group の例/デモから始め、addLabelControl が渡されたときの動作を追跡します。VoiceOver の読み上げ要件を確認し、すべてのラベルを読み上げ直すことなく新しく追加されたラベルをどのように通知するかを決めます。関連するインタラクションで結果がアクセシブルに伝われば完了です。