Please add `app.get_new_client()` to help with token rotation

From a discussion in #1324, the only safe way to call the client from outside a bolt handler when token rotation is on is to create a new client each time (as the handlers do)

Since Bolt is currently handling all of this for us, it'd be very useful to have a method along the lines of

client = await bolt.get_new_client(team_id)

that means callers do not need to deal with the InstallationStore and such themselves.

Category (place an x in each of the [ ])

• slack_bolt.App and/or its core components
• slack_bolt.async_app.AsyncApp and/or its core components
• Adapters in slack_bolt.adapter
• Others

Requirements

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Examinez d’abord la discussion #1324, puis inspectez les points d’entrée slack_bolt.App et slack_bolt.async_app.AsyncApp ainsi que la manière dont ils utilisent InstallationStore lors de la rotation des tokens. La tâche est considérée comme terminée lorsque les appelants peuvent obtenir un client nouvellement créé pour une équipe via les méthodes demandées sans avoir à gérer eux-mêmes le store, aussi bien pour les applications synchrones qu’asynchrones.