command/playlist: move code to SearchInsertIntoPlaylist()

src/command/PlaylistCommands.cxx

@@ -231,15 +231,12 @@ handle_playlistadd_position(Client &client, const char *playlist_name,
 		editor.Insert(position, uri);
 	} else {
 #ifdef ENABLE_DATABASE
-		const auto &db = client.GetDatabaseOrThrow();
-		const auto *storage = client.GetStorage();
 		const DatabaseSelection selection(uri, true, nullptr);
 
-		db.Visit(selection, [&editor, &position, storage](const auto &song){
-			editor.Insert(position,
-				      DatabaseDetachSong(storage, song));
-			++position;
-		});
+		SearchInsertIntoPlaylist(client.GetDatabaseOrThrow(),
+					 client.GetStorage(),
+					 selection,
+					 editor, position);
 #else
 		(void)client;
 		r.Error(ACK_ERROR_NO_EXIST, "No database");