AlertingNG: Edit Alert Definition (#30676)

* break out new and edit

* changed model to match new model in backend

* AlertingNG: API modifications (#30683)

* Fix API consistency

* Change eval alert definition to POST request

* Fix eval endpoint to accept custom now parameter

* Change JSON input property for create/update endpoints

* model adjustments

* set mixed datasource, fix put url

* update snapshots

* remove edit and add landing page

* remove snapshot tests ans snapshots

* wrap linkbutton in array

Co-authored-by: Sofia Papagiannaki <papagian@users.noreply.github.com>
Co-authored-by: Sofia Papagiannaki <sofia@grafana.com>

pkg/api/index.go

@@ -196,16 +196,6 @@ func (hs *HTTPServer) getNavTree(c *models.ReqContext, hasEditPerm bool) ([]*dto
 		})
 	}
 
-	if hs.Cfg.IsNgAlertEnabled() {
-		navTree = append(navTree, &dtos.NavLink{
-			Text:     "NgAlerting",
-			Id:       "ngalerting",
-			SubTitle: "Next generation alerting",
-			Icon:     "bell",
-			Url:      setting.AppSubUrl + "/ngalerting",
-		})
-	}
-
 	if c.IsSignedIn {
 		navTree = append(navTree, getProfileNode(c))
 	}