Admin Page: Introduce a banner for the WP.com security checklist

From https://github.com/Automattic/wp-calypso/issues/32565

**wp-admin first visit**
I think it's important we provide a linear pathway for customers who aren't familiar with jetpack. I'm suggesting that the **first time they visit** the jetpack dashboard in wp-admin, we display a dismissible banner welcoming them to their jetpack dashboard and informing them of the checklist.


Clicking "continue jetpack setup" will bring them to the actual checklist to complete tasks. Clicking the "wp-admin" sidebar link will return them to their jetpack dashboard under "my plan," where a permanent mention of the checklist will reside...

**a home for the checklist indicator in wp-admin**
I think the checklist deserves a permanent mention under the "my plan" tab in the jetpack dashboard in wp-admin (consistent with its location in calypso as well). I'm envisioning a visual that's simple and consistent with all the UI that we see in calypso for consistency.