Resolve #3476217 "Page template margin"

Closes #3476217

To test:

• On drupalorg site checkout https://gitlab.com/drupal-infrastructure/sites/drupalorg/-/merge_requests/43
• Run ddev composer install
• run composer recreate
• View the motherlode
• This should still have full width components such as the hero where the background goes to the edge of the viewport
• The hero background should still go behing the global header when not logged in.
• View other content types
• The left and right content of the page should align with the page header
• On any page including the user login page at /user, there should be padding added to the top of the page so that the header does not cover the content
• On any page but a landing page there should now be a "page header" component that includes the page title and breadcrumb above it. It should be light blue all the way to the edge of the page but text inside should be inside content max width of 1610

Still to do:

• further style refinement of h1, h2 etc. and breadcrumbs. I would like to address with the general base styles and vertical rhythm ticket that will follow this.