feat: Add push/email notification support for SLA (#9140)

* feat: update SLA evaluation logic

* Update enterprise/app/services/sla/evaluate_applied_sla_service.rb

Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>

* chore: refactor spec to bring down expecations in a single block

* chore: fix process_account_applied_sla spec

* chore: add spec to test multiple nrt misses

* feat: persist sla notifications

* feat: revert persist sla notifications

* feat: add SLA push/email notification support

* chore: refactor sla_status to include active_with_misses

* chore: add support for sla push/email notifications

* chore: refactor

* chore: add liquid templates

* chore: add spec for liquid templates

* chore: add spec for sla email notifications

* chore: add spec for SlaPolicyDrop

* chore: refactor to ee namespace

* chore: set enterprise test type to mailer

* feat: enable sla notification settings only if SLA enabled

* chore: refactor

* chore: fix spec

---------

Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>

app/models/notification.rb

@@ -118,11 +118,11 @@ class Notification < ApplicationRecord
 
   def push_message_body
     case notification_type
-    when 'conversation_creation'
+    when 'conversation_creation', 'sla_missed_first_response'
       message_body(conversation.messages.first)
     when 'assigned_conversation_new_message', 'participating_conversation_new_message', 'conversation_mention'
       message_body(secondary_actor)
-    when 'conversation_assignment'
+    when 'conversation_assignment', 'sla_missed_next_response', 'sla_missed_resolution'
       message_body(conversation.messages.incoming.last)
     else
       ''