feat: improvements to priority (#6981)

* fix: colors for urgent icon

* feat: trigger updated event on priority change

* fix: specs

spec/models/conversation_spec.rb

@@ -518,6 +518,7 @@ RSpec.describe Conversation, type: :model do
         contact_last_seen_at: conversation.contact_last_seen_at.to_i,
         agent_last_seen_at: conversation.agent_last_seen_at.to_i,
         created_at: conversation.created_at.to_i,
+        priority: nil,
         unread_count: 0
       }
     end