[Bot] [Discussion] [PR #15200] feat: Country and Age during Signup

Testing Site URL: https://gh-imp-2021-02122.castlecraft.co.in

Pull Request URL: https://github.com/frappe/frappe/pull/15200
Pull Request Title: feat: Country and Age during Signup
Pull Request Description: **Asking Country and Verifying Age during Signup:**

  1. This can be enabled from Website Settings.

  1. Once enabled, the signup form will have these fields additionally.

  1. Based on the user’s input, values will be stored in User doctype.

Steps to test:

  1. From website settings, enable Show Country dropdown during Signup and Verify Age during Signup. Save.
  2. Go to the Signup form. Fill in the details and signup.
  3. Try the signup form with the settings disabled.