Create an overview page and add singup/waitlist

Acceptance Criteria

• Should create a new overview page.
• Should add the signup and waitlisting ability to this page.
• Should add the import CTA button to the overview page if user is approved.
• there should be an `Overview` navigation link present at all times
• the user should land on the `Overview` page by default
• Change Development Preview to Private Preview on the blue banner
  • Update tooltip copy:
    Private preview releases provide early access to a limited set of features that might not be fully tested. Users should not use private preview software in production or for business-critical workloads.