fix(StaticNotification): set describedby on action button

[finken2]

Follow-on to a previous PR that added the actionButton capability to StaticNotification. I didn't realize that the aria-describedby was being enforced on the button in addition to the body. My storybook example didn't catch that, b/c the currentuseInteractiveChildrenNeedDescription is only checking the first interactive child. So when i went to use it with just the button, kaboom.

Fully tested it out locally in our microservice, recreating the issue and fixing it.
I also changed the proptype of subtitle to Node to match actionableNotification, making the swap easier.

Changelog

New

• pass titleId to the NotificationButton as aria-describedby. No new prop for this.
• additional storybook story for the action button only

Changed

• updated subtitle to be PropTypes.Node to match ActionableNotification.

Testing / Reviewing

render a StaticNotification within live code with action button and embedded links.

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[finken2]

Not picking up my 2nd commit, so going to recreate this PR....