Add trending links (#16917)

* Add trending links

* Add overriding specific links trendability

* Add link type to preview cards and only trend articles

Change trends review notifications from being sent every 5 minutes to being sent every 2 hours

Change threshold from 5 unique accounts to 15 unique accounts

* Fix tests

app/mailers/admin_mailer.rb

@@ -25,13 +25,25 @@ class AdminMailer < ApplicationMailer
     end
   end
 
-  def new_trending_tag(recipient, tag)
-    @tag      = tag
-    @me       = recipient
-    @instance = Rails.configuration.x.local_domain
+  def new_trending_tags(recipient, tags)
+    @tags                = tags
+    @me                  = recipient
+    @instance            = Rails.configuration.x.local_domain
+    @lowest_trending_tag = Trends.tags.get(true, Trends::Tags::REVIEW_THRESHOLD).last
 
     locale_for_account(@me) do
-      mail to: @me.user_email, subject: I18n.t('admin_mailer.new_trending_tag.subject', instance: @instance, name: @tag.name)
+      mail to: @me.user_email, subject: I18n.t('admin_mailer.new_trending_tags.subject', instance: @instance)
+    end
+  end
+
+  def new_trending_links(recipient, links)
+    @links                = links
+    @me                   = recipient
+    @instance             = Rails.configuration.x.local_domain
+    @lowest_trending_link = Trends.links.get(true, Trends::Links::REVIEW_THRESHOLD).last
+
+    locale_for_account(@me) do
+      mail to: @me.user_email, subject: I18n.t('admin_mailer.new_trending_links.subject', instance: @instance)
     end
   end
 end