MDL-41811 navigation: Site admin will be loaded by ajax on non admin pages
MDL-41811 find out if admin tree needed in navigation
MDL-41811 tweak custom admin pages to force loading of admin tree
MDL-41811 Navigation: set admin navigation required in badges
MDL-41811 navigation: Avoid loading site admin navigation is not required

If settings node is added for frontpage, category, course, module, block or user
then don't load site admin navigation.
MDL-41811 navigation: Fixed navigation issues on pages

Few admin pages don't add navigation node and hence they should
not show site admin
MDL-41811 navigation: Load site admin navigation

Go to notification page before following links within site admin
navigation, ensuring site admin navigation is loaded

With no js, test should follow site admin link and not expand it.
MDL-41811 simplify the admin tree detection logic and fix navigation in multiple areas