Better typing for block actions payload

[sota1235]

I wish some block action body will have more correct typing.

For example, when I use InteractiveMessage type when I want to handle event for clicking button on message, that's type does not contain container payload. But actually it exists. I think it's intentional type, here is an official document. https://api.slack.com/reference/interaction-payloads/block-actions#examples

Is there any blocker to implement this type? If not, I have a motivation to pull request.

Requirements

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