Add server rules (#15769)

db/migrate/20210221045109_create_rules.rb

@@ -0,0 +1,11 @@
+class CreateRules < ActiveRecord::Migration[5.2]
+  def change
+    create_table :rules do |t|
+      t.integer :priority, null: false, default: 0
+      t.datetime :deleted_at
+      t.text :text, null: false, default: ''
+
+      t.timestamps
+    end
+  end
+end