refactor!: finish parser migration

Finally! :)

This removes all code related to the old parser.

#65

lib/parser/classes/PlaylistPanel.js

@@ -0,0 +1,22 @@
+'use strict';
+
+const Parser = require('..');
+const Text = require('./Text');
+
+class PlaylistPanel {
+  type = 'PlaylistPanel';
+
+  constructor(data) {
+    this.title = data.title;
+    this.title_text = new Text(data.titleText);
+    this.contents = Parser.parse(data.contents);
+    this.playlist_id = data.playlistId;
+    this.is_infinite = data.isInfinite;
+    this.continuation = data.continuations[0]?.nextRadioContinuationData?.continuation;
+    this.is_editable = data.isEditable;
+    this.preview_description = data.previewDescription;
+    this.num_items_to_show = data.numItemsToShow;
+  }
+}
+
+module.exports = PlaylistPanel;