feat: add support for chapters & video heatmap (#263)

* feat: add support for chapters & video heatmap

* chore: add tests

src/parser/classes/Chapter.ts

@@ -0,0 +1,21 @@
+import Text from './misc/Text';
+import Thumbnail from './misc/Thumbnail';
+
+import { YTNode } from '../helpers';
+
+class Chapter extends YTNode {
+  static type = 'Chapter';
+
+  title: Text;
+  time_range_start_millis: number;
+  thumbnail: Thumbnail[];
+
+  constructor(data: any) {
+    super();
+    this.title = new Text(data.title);
+    this.time_range_start_millis = data.timeRangeStartMillis;
+    this.thumbnail = Thumbnail.fromResponse(data.thumbnail);
+  }
+}
+
+export default Chapter;