#5918520 Add warning to email plan header for expired email subscription

Changes proposed in this Pull Request

• This PR adds logic to the email plan header to display “Expired: [expiryDate]” in red when the subscription has already expired (instead of “Expires: [expiryDate]”), and switches the “Renew now” button to be primary for expired subscriptions

This behaviour is closely related to #52863, where we are flagging expired Professional Email subscriptions, but not showing a relevant warning/CTA on the email plan page.

Testing instructions

• Run this branch locally or via the live branch
• Navigate to /email and then pick a site that has an expired email subscription (ideally you’d have multiple subscription types)
• Click on the site with the expired email subscription, and then click on the row for the expired subscription
• Verify that the header shows “Expired: [expiryDate]” in red font the second row and the “Renew now” button is shown as a primary CTA
• Go back to your list of emails and visit the Email Plan page for a non-expired, paid email subscription
• Verify that the header shows “Expires: [expiryDate]” in a normal colour and the “Renew now” button is not primary
• Go back to the email list and pick a domain with email forwarding
• Verify that the renewal/subscription section doesn’t show at all (this is the existing behaviour)

Screenshot