feat: send polls (#2377)

* feat: added Poll class

* feat: logic for sending polls added

* updated poll properties on returned message instance

* docs updated

* usage example updated

* module fixed

* 'pollSendOptions' changed to 'options'

* window.compareWwebVersions fixed

* small update to improve the performance of findImpl fix

* added option for custom message secret

* usage example updated

src/util/Constants.js

@@ -108,6 +108,7 @@ exports.MessageTypes = {
     PROTOCOL: 'protocol',
     REACTION: 'reaction',
     TEMPLATE_BUTTON_REPLY: 'template_button_reply',
+    POLL_CREATION: 'poll_creation',
 };
 
 /**