Navigation: Add help menu to top search bar (#55062)

* add help menu to top search bar

* fixes

* handle preventDefault in node graph specifically

* use icon prop of MenuItem

* undo changes to ContextMenuPlugin/DataLinksContextMenu

* remove unused component

* revert storybook changes

* Tweaks

* remove unused style

* stop propagation on the header so version can be highlighted

* make sure useContextMenu has the exact same logic as before

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

packages/grafana-data/src/types/navModel.ts

@@ -1,5 +1,6 @@
 import { ComponentType } from 'react';
 
+import { LinkTarget } from './dataLink';
 import { IconName } from './icon';
 
 export interface NavLinkDTO {
@@ -11,7 +12,7 @@ export interface NavLinkDTO {
   icon?: IconName;
   img?: string;
   url?: string;
-  target?: string;
+  target?: LinkTarget;
   sortWeight?: number;
   divider?: boolean;
   hideFromMenu?: boolean;