Playlist: Split PlaylistItem into standalone TS type (#56343)

* playlist: Split PlaylistItem into standalone TS type

* update playlist model

* actually set the title

Co-authored-by: Ryan McKinley <ryantxu@gmail.com>

pkg/coremodel/playlist/coremodel.cue

@@ -39,10 +39,10 @@ seqs: [
 					//  dashboards behind the tag will be added to the playlist.
 					//  - dashboard_by_uid: The value is the dashboard UID
 					value: string
-					
+
 					// Title is an unused property -- it will be removed in the future
-    				title: string
-				}
+    				title?: string
+				} @cuetsy(kind="interface")
 			}
 		]
 	}

pkg/coremodel/playlist/playlist_gen.go

@@ -52,7 +52,7 @@ type Model struct {
 // Equivalent Go types at stable import paths are provided in https://github.com/grafana/grok.
 type PlaylistItem struct {
 	// Title is an unused property -- it will be removed in the future
-	Title string `json:"title"`
+	Title *string `json:"title,omitempty"`
 
 	// Type of the item.
 	Type PlaylistItemType `json:"type"`