feat: Notification on new messages in conversation (#1204)

fixes: #895
fixes: #1118
fixes: #1075

Co-authored-by: Pranav Raj S <pranav@thoughtwoot.com>

app/models/notification.rb

@@ -31,7 +31,8 @@ class Notification < ApplicationRecord
 
   NOTIFICATION_TYPES = {
     conversation_creation: 1,
-    conversation_assignment: 2
+    conversation_assignment: 2,
+    assigned_conversation_new_message: 3
   }.freeze
 
   enum notification_type: NOTIFICATION_TYPES
@@ -64,6 +65,8 @@ class Notification < ApplicationRecord
 
     return "A new conversation [ID -#{primary_actor.display_id}] has been assigned to you." if notification_type == 'conversation_assignment'
 
+    return "New message in your assigned conversation [ID -#{primary_actor.display_id}]." if notification_type == 'assigned_conversation_new_message'
+
     ''
   end
 
@@ -71,6 +74,7 @@ class Notification < ApplicationRecord
 
   def process_notification_delivery
     Notification::PushNotificationJob.perform_later(self)
+
     # Should we do something about the case where user subscribed to both push and email ?
     # In future, we could probably add condition here to enqueue the job for 30 seconds later
     # when push enabled and then check in email job whether notification has been read already.