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/middleware/middleware_test.go

@@ -120,7 +120,7 @@ func TestMiddlewareContext(t *testing.T) {
 			data := &dtos.IndexViewData{
 				User:     &dtos.CurrentUser{},
 				Settings: map[string]interface{}{},
-				NavTree:  []*navtree.NavLink{},
+				NavTree:  &navtree.NavTreeRoot{},
 			}
 			t.Log("Calling HTML", "data", data)
 			c.HTML(http.StatusOK, "index-template", data)