Add widget for branch push event to the homepage

What does this MR do and why?

There is a success alert that is posted to other "dashboard" pages when a user pushes a new branch from their local.

Instead of reusing the same alert with = render "projects/last_push" we should thoughtfully integrate the transition of this task. This change adds a new section to the homepage, and its first element presents the user with the option to create a merge request from that branch to mimic the functionality.

References

#553938 (comment 2693293350)
Add widget for branch push event to the homepage (#566310 - closed)

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Enable the personal_homepage feature flag.
2. Push a branch from your local to gdk or by editing a file and commiting the changes without creating a new merge request
3. Go to http://gdk.test:3000/dashboard/home
4. Dismiss the message
5. Refresh the page to make it appear (it goes away after 2 hours)
6. Try to create an MR

MR acceptance checklist

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