feat: Add support for retrieving transcripts (#500)

* feat: Add support for retrieving transcripts

* chore: lint

* chore: update docs

* chore: Do not include nodes in errors thrown

* chore: Improve error messages

* fix(ExpandableMetadata): `expanded_content` type mismatch

* chore: lint

src/parser/classes/TranscriptSearchBox.ts

@@ -0,0 +1,23 @@
+import { YTNode } from '../helpers.js';
+import type { RawNode } from '../index.js';
+import Parser from '../index.js';
+import Button from './Button.js';
+import NavigationEndpoint from './NavigationEndpoint.js';
+import { Text } from '../misc.js';
+
+export default class TranscriptSearchBox extends YTNode {
+  static type = 'TranscriptSearchBox';
+
+  formatted_placeholder: Text;
+  clear_button: Button | null;
+  endpoint: NavigationEndpoint;
+  search_button: Button | null;
+
+  constructor(data: RawNode) {
+    super();
+    this.formatted_placeholder = new Text(data.formattedPlaceholder);
+    this.clear_button = Parser.parseItem(data.clearButton, Button);
+    this.endpoint = new NavigationEndpoint(data.onTextChangeCommand);
+    this.search_button = Parser.parseItem(data.searchButton, Button);
+  }
+}