Add header and footer regions from default drupal core

[joelpittet]

Problem/Motivation:
When switching from theme inheritance with a base theme of galactus to starterkit fork, the regions don't match well because galactus defined regions aren't inherited: https://www.drupal.org/docs/theming-drupal/sub-theme-inheritance

Proposed Solution:
From the default regions in core and the page.html.twig file suggests a page.header and page.footer region will exist and we should add them to the page.html.twig template and info file..

public/core/lib/Drupal/Core/Extension/ThemeExtensionList.php:26

      'sidebar_first' => 'Left sidebar',
      'sidebar_second' => 'Right sidebar',
      'content' => 'Content',
      'header' => 'Header',
      'primary_menu' => 'Primary menu',
      'secondary_menu' => 'Secondary menu',
      'footer' => 'Footer',
      'highlighted' => 'Highlighted',
      'help' => 'Help',
      'page_top' => 'Page top',
      'page_bottom' => 'Page bottom',
      'breadcrumb' => 'Breadcrumb',

The page_top, page_bottom are the only other ones in there but they get easily confused with the html.html.twig variables, so opted not to include them.

[occupant]

All looks good to me. I've tested and found no issues

Thanks!