NavTree: Make it possible to configure where in nav tree plugins live (#55484)

* NewIA: Plugin nav config

* progress

* Progress

* Things are working

* Add monitoring node

* Add alerts and incidents

* added experiment with standalone page

* Refactoring by adding a type for navtree root

* First test working

* More tests

* more tests

* Progress on richer config and sorting

* Sort weight working

* Path config

* Improving logic for not including admin or cfg nodes, making it the last step so that enterprise can add admin nodes without having to worry about the section not existing

* fixed index routes

* removed file

* Fixes

* Fixing tests

* Fixing more tests and adding support for weight config

* Updates

* Remove unused fake

* More fixes

* Minor tweak

* Minor fix

* Can now control position using sortweight even when existing items have no sortweight

* Added tests for frontend standalone page logic

* more tests

* Remove unused fake and fixed lint issue

* Moving reading settings to navtree impl package

* remove nav_id setting prefix

* Remove old test file

* Fix trailing newline

* Fixed bug with adding nil node

* fixing lint issue

* remove some code we have to rethink

* move read settings to PrivideService and switch to util.SplitString

pkg/api/login_test.go

@@ -44,7 +44,7 @@ func fakeSetIndexViewData(t *testing.T) {
 		data := &dtos.IndexViewData{
 			User:     &dtos.CurrentUser{},
 			Settings: map[string]interface{}{},
-			NavTree:  []*navtree.NavLink{},
+			NavTree:  &navtree.NavTreeRoot{},
 		}
 		return data, nil
 	}