feat(parser): add GridShow and ShowCustomThumbnail

Closes #459

src/parser/classes/ThumbnailOverlayBottomPanel.ts

@@ -1,13 +1,22 @@
 import { YTNode } from '../helpers.js';
+import { RawNode } from '../index.js';
+import Text from './misc/Text.js';
 
 class ThumbnailOverlayBottomPanel extends YTNode {
   static type = 'ThumbnailOverlayBottomPanel';
 
-  icon_type: string;
+  text?: Text;
+  icon_type?: string;
 
-  constructor(data: any) {
+  constructor(data: RawNode) {
     super();
-    this.icon_type = data.icon.iconType;
+    if (Reflect.has(data, 'text')) {
+      this.text = new Text(data.text);
+    }
+
+    if (Reflect.has(data, 'icon') && Reflect.has(data.icon, 'iconType')) {
+      this.icon_type = data.icon.iconType;
+    }
   }
 }