Added overridable send permission method to notifications [SCI-5938]

app/models/notification.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Notification < ApplicationRecord
   has_many :user_notifications, inverse_of: :notification, dependent: :destroy
   has_many :users, through: :user_notifications
@@ -7,13 +9,20 @@ class Notification < ApplicationRecord
 
   def already_seen(user)
     UserNotification.where(notification: self, user: user)
-                    .pluck(:checked)
-                    .first
+                    .pick(:checked)
   end
 
   def create_user_notification(user)
     return if user == generator_user
+    return unless can_send_to_user?(user)
+    return unless user.enabled_notifications_for?(type_of.to_sym, :web)
 
-    user_notifications.create!(user: user) if user.enabled_notifications_for?(type_of.to_sym, :web)
+    user_notifications.create!(user: user)
+  end
+
+  private
+
+  def can_send_to_user?(_user)
+    true # overridable send permission method
   end
 end