feat: widget opened and closed events (#11240)

Fixes #9272

---------

Co-authored-by: Sivin Varghese <64252451+iamsivin@users.noreply.github.com>

app/views/widget_tests/index.html.erb

@@ -66,6 +66,13 @@ window.addEventListener('chatwoot:postback', function(e) {
   console.log('chatwoot:postback', e.detail)
 })
 
+window.addEventListener('chatwoot:opened', function() {
+  console.log('chatwoot:opened')
+})
+
+window.addEventListener('chatwoot:closed', function() {
+  console.log('chatwoot:closed')
+})
 
 window.addEventListener('chatwoot:on-start-conversation', function(e) {
   console.log('chatwoot:on-start-conversation', e.detail)