feat: Add support for labels in automations (#11658)

- Add support for using labels as an action event for automation
 - Fix duplicated conversation_updated event dispatch for labels
 

Fixes https://github.com/chatwoot/chatwoot/issues/8539 and multiple
issues around duplication related to label change events.
---------

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

app/models/concerns/labelable.rb

@@ -10,6 +10,8 @@ module Labelable
   end
 
   def add_labels(new_labels = nil)
+    return if new_labels.blank?
+
     new_labels = Array(new_labels) # Make sure new_labels is an array
     combined_labels = labels + new_labels
     update!(label_list: combined_labels)