#5527521 Email: Redesign section headers and add links to services in Email page

This pull request updates the Email page for Titan and Google Workspace in order to:

• Display icons of email providers: this improves branding as well as consistency with the Purchases Settings page
• Show product names and domain names on two lines: this is to avoid issues with long names and small viewports
• Add an Add New Mailboxes button for Titan: that way the user experience is more consistent across email providers
• Add icons and links to email provider services: so users can access their mailboxes and other apps easily

Before	After	After (Expanded)

Note the design was inspired by the Connections page. There is some duplicate code between the G Suite and Titan components. Ideally, we should reuse the same components but since this pull request is already long enough I thought this refactoring should take place in another one.

Testing instructions

1. Run git checkout update/email-page and start your server, or open a live branch
2. Log into a WordPress.com account with a Titan or a Google Workspace account
3. Open the Email page
4. Assert that this page looks like the screenshots above
5. Assert that it still looks fine on small viewports
6. Check that the placeholder displays correctly