NavBarMenu: Section as links and design tweak (#55538)

* scaffold new component + remove storing of expanded state

* some padding fixes

* simplify!

* move browse back to being a child of dashboards

* behaviour working

* improve child matcher to look recursively

* increase NavBarMenu zIndex to ensure it overlays explore drawer

* some renaming

* fix unit test

* make dashboards a top level item again and make chevrons their own buttons

* remove active background state

* Finished tweaks

* remove theme change

* Remove exit animation

* align button centrally + fix empty message alignment

* only show the empty message if there are no children

* ensure overflowing menu items truncate correctly

Co-authored-by: Ashley Harrison <ashley.harrison@grafana.com>

pkg/api/index.go

@@ -105,7 +105,7 @@ func (hs *HTTPServer) getAppLinks(c *models.ReqContext) ([]*dtos.NavLink, error)
 		}
 
 		if hs.Features.IsEnabled(featuremgmt.FlagTopnav) {
-			appLink.Url = path.Join(hs.Cfg.AppSubURL, "a", plugin.ID)
+			appLink.Url = hs.Cfg.AppSubURL + "/a/" + plugin.ID
 		} else {
 			appLink.Url = path.Join(hs.Cfg.AppSubURL, plugin.DefaultNavURL)
 		}
@@ -521,6 +521,7 @@ func (hs *HTTPServer) buildDashboardNavLinks(c *models.ReqContext, hasEditPerm b
 			Text: "Browse", Id: "dashboards/browse", Url: hs.Cfg.AppSubURL + "/dashboards", Icon: "sitemap",
 		})
 	}
+
 	dashboardChildNavs = append(dashboardChildNavs, &dtos.NavLink{
 		Text: "Playlists", Id: "dashboards/playlists", Url: hs.Cfg.AppSubURL + "/playlists", Icon: "presentation-play",
 	})