Refactor JSON templates to be generated with ActiveModelSerializers instead of Rabl (#4090)

app/serializers/rest/instance_serializer.rb

@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+class REST::InstanceSerializer < ActiveModel::Serializer
+  attributes :uri, :title, :description, :email,
+             :version, :urls
+
+  def uri
+    Rails.configuration.x.local_domain
+  end
+
+  def title
+    Setting.site_title
+  end
+
+  def description
+    Setting.site_description
+  end
+
+  def email
+    Setting.site_contact_email
+  end
+
+  def version
+    Mastodon::Version.to_s
+  end
+
+  def urls
+    { streaming_api: Rails.configuration.x.streaming_api_base_url }
+  end
+end