Add admin API for managing IP blocks (#19065)

app/serializers/rest/admin/ip_block_serializer.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+class REST::Admin::IpBlockSerializer < ActiveModel::Serializer
+  attributes :id, :ip, :severity, :comment,
+             :created_at, :expires_at
+
+  def id
+    object.id.to_s
+  end
+
+  def ip
+    "#{object.ip}/#{object.ip.prefix}"
+  end
+end