Add notification policies and notification requests (#29366)

db/migrate/20240222193403_create_notification_permissions.rb

@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+class CreateNotificationPermissions < ActiveRecord::Migration[7.1]
+  def change
+    create_table :notification_permissions do |t|
+      t.references :account, null: false, foreign_key: true
+      t.references :from_account, null: false, foreign_key: { to_table: :accounts }
+
+      t.timestamps
+    end
+  end
+end