Dashboard Controls: Fix schema transformation for link placement (#114630)

* fix: add missing transformation for scenes -> save model v2

* fix: link placement transformation on the backend between schemas

* fix: update the openapi spec in the tests

* tes: add tests for `transformSceneToSaveModelSchemaV2`

* tests: extend conversion_test.go to cover link placements

apps/dashboard/kinds/v2alpha1/dashboard_spec.cue

@@ -109,8 +109,14 @@ DashboardLink: {
 	includeVars: bool | *false
 	// If true, includes current time range in the link as query params
 	keepTime: bool | *false
+	// Placement can be used to display the link somewhere else on the dashboard other than above the visualisations.
+	placement?: DashboardLinkPlacement
 }
 
+// Dashboard Link placement. Defines where the link should be displayed. 
+// - "inControlsMenu" renders the link in bottom part of the dashboard controls dropdown menu
+DashboardLinkPlacement: "inControlsMenu"
+
 DataSourceRef: {
 	// The plugin type-id
 	type?: string