DashboardScene: Support dashboard links (#77855)

* MenuItem: Allow react node as label

* LinkButton: Expose ButtonLinkProps

* Typecheck fix

* DashboardLinks: Refactor and use LinkButton and menu

* DashbaordLinks scene object

* Use flex layout for dashboard controls

* Update public/app/features/dashboard/components/SubMenu/DashboardLinksDashboard.tsx

Co-authored-by: Alex Khomenko <Clarity-89@users.noreply.github.com>

* fix keepTime and includeVars

* Add ellipsis to menu item label and description

* Use DashboardLink type from grafana/schema

* Update dashboard scene controls layout

* Fix e2e

* Test fix

* Bring back keyboard navigation

* Remove unused code

* One more fix

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Co-authored-by: Alex Khomenko <Clarity-89@users.noreply.github.com>
Co-authored-by: Torkel Ödegaard <torkel@grafana.com>

kinds/dashboard/dashboard_kind.cue

@@ -265,7 +265,7 @@ lineage: schemas: [{
 			// Tooltip to display when the user hovers their mouse over it
 			tooltip: string
 			// Link URL. Only required/valid if the type is link
-			url: string
+			url?: string
 			// List of tags to limit the linked dashboards. If empty, all dashboards will be displayed. Only valid if the type is dashboards
 			tags: [...string]
 			// If true, all dashboards links will be displayed in a dropdown. If false, all dashboards links will be displayed side by side. Only valid if the type is dashboards