Implement a basic store dashboard at /admin/commerce

I opened two related issues in Commerce Core and Commerce Shipping for moving items out from the main Commerce submenu into the Commerce > Configuration submenu. This will let us render management links for all first level child menu items of Commerce as opposed to just trying to pick a few that should be rendered as links. (This means a little more work to make sure it functions properly with variable numbers of links, but it also ensures all child menus are easily accessible in the event a site isn't using Admin Toolbar.)

Opened a merge request to trigger pipelines, let's see what PHPCS violations were introduced :).

Attaching screenshots so we can embed them elsewhere on d.o. Will be sure to document the settings for the toolbar link and feed fetch in the new docs site. For those looking for them in the meantime, you can disable either one by setting these in settings.php:

$settings['commerce_dashboard_show_toolbar_link'] = FALSE;
$settings['commerce_dashboard_fetch_inbox_messages'] = FALSE;

Bear in mind that inbox messages come from multiple sources, including module installations and updates. The inbox will not go away, just the fetching of updates from our project feed will be disabled on cron.

Automatically closed - issue fixed for 2 weeks with no activity.