Bug - Notification Drawer should allow focus trap

Describe the problem
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When using a keyboard to navigate the page in https://www.patternfly.org/components/notification-drawer/react-demos/basic/, keyboard focus is given to the first button or link in the drawer, which is correct.

However, when a user goes and closes the notification drawer, keyboard focus does not return to the notification button, and seems to return to the browser chrome, which is disorienting.

Moreover, after tabbing to the last item in the notification drawer, the next tab press should loop back to the first item in the notification drawer; however, this is not done.

Expected behavior
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In the demo, keyboard focus should be returned to the notification badge after the notification drawer is closed, and the keyboard focus should be trapped entirely within the notification drawer when it is open.

Screenshots
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Any other information?

See this blog post:

https://codepen.io/unleashalicia/pen/YzXrJBN
https://knowbility.org/blog/2020/accessible-slide-menus

Jira Issue: PF-1354

Beginne mit der grundlegenden React-Demo für den Benachrichtigungsbereich auf der verlinkten PatternFly-Seite und überprüfe die verlinkten Beispiele zur Fokusverwaltung. Überprüfe das aktuelle Tastaturverhalten des Benachrichtigungsbereichs und stelle dann sicher, dass der Fokus beim Schließen zum Benachrichtigungs-Badge zurückkehrt und innerhalb des geöffneten Benachrichtigungsbereichs zirkuliert; validiere beide Verhaltensweisen in der Demo.