Add server rules (#15769)

spec/fabricators/rule_fabricator.rb

@@ -0,0 +1,5 @@
+Fabricator(:rule) do
+  priority   ""
+  deleted_at "2021-02-21 05:51:09"
+  text       "MyText"
+end

spec/models/rule_spec.rb

@@ -0,0 +1,5 @@
+require 'rails_helper'
+
+RSpec.describe Rule, type: :model do
+  pending "add some examples to (or delete) #{__FILE__}"
+end