refactor!: finish parser migration

Finally! :)

This removes all code related to the old parser.

#65

lib/parser/classes/SubscribeButton.js

@@ -0,0 +1,24 @@
+'use strict';
+
+const Parser = require('..');
+const Text = require('./Text');
+const NavigationEndpoint = require('./NavigationEndpoint');
+
+class SubscribeButton {
+  type = 'SubscribeButton';
+
+  constructor(data) {
+    this.title = new Text(data.buttonText);
+    this.subscribed = data.subscribed;
+    this.enabled = data.enabled;
+    this.type = data.type;
+    this.channel_id = data.channelId;
+    this.show_preferences = data.showPreferences;
+    this.subscribed_text = new Text(data.subscribedButtonText);
+    this.unsubscribed_text = new Text(data.unsubscribedButtonText);
+    this.notification_preference_button = Parser.parse(data.notificationPreferenceButton);
+    this.endpoint = new NavigationEndpoint(data.serviceEndpoints?.[0] || data.onSubscribeEndpoints?.[0]);
+  }
+}
+
+module.exports = SubscribeButton;