MissingPage: support multiple action buttons

Description

MissingPage currently supports only a single link/action via the toHomePageUrl prop (rendered as a "Go to home page" link). A common 404 page pattern includes multiple actions — typically both "Go Home" and "Go Back" buttons.

Use Case

In ansible/ansible-ui, our custom PageNotFound component renders two action buttons:

• "Go to Dashboard" (navigate to home)

• "Return to previous page" (browser back)

We cannot adopt MissingPage because it only renders one action.

Proposed Solution

Add support for custom footer actions, either via:

• A customFooter or actions prop that accepts ReactNode (most flexible)

• An additionalActions array prop alongside the existing toHomePageUrl

This would align with how other component-groups components like ErrorState support customFooter.

Current Workaround

We maintain a custom PageNotFound component that duplicates MissingPage's layout but adds a second button.

Jira Issue: PF-4547

Commencez par lire le composant MissingPage et comparez son API de footer avec ErrorState, qui prend déjà en charge customFooter. Vérifiez comment l’action toHomePageUrl existante est rendue, puis ajoutez un moyen pris en charge de rendre plusieurs actions personnalisées tout en préservant le comportement actuel. Le travail est terminé lorsque les consommateurs peuvent fournir à la fois des actions d’accueil et de retour sans dupliquer la mise en page de MissingPage.