Move push priority concerns from Event and Mention into Native push target

app/models/event.rb

@@ -37,10 +37,6 @@ class Event < ApplicationRecord
     Event::Description.new(self, user)
   end
 
-  def high_priority_push?
-    action.card_assigned?
-  end
-
   private
     def dispatch_webhooks
       Event::WebhookDispatchJob.perform_later(self)

app/models/mention.rb

@@ -18,10 +18,6 @@ class Mention < ApplicationRecord
     source
   end
 
-  def high_priority_push?
-    true
-  end
-
   private
     def watch_source_by_mentionee
       source.watch_by(mentionee)

saas/app/models/notification/push_target/native.rb

@@ -73,7 +73,11 @@ class Notification::PushTarget::Native < Notification::PushTarget
     end
 
     def high_priority_notification?
-      notification.source.high_priority_push?
+      case notification.source
+      when Event then notification.source.action.card_assigned?
+      when Mention then true
+      else false
+      end
     end
 
     def creator_avatar_url