Add ignored routes to the configuration file

Assigning to myself as I'm reviewing/merging ready RTBC fixes/updates over the next few days.

See above for code comments.

Also, we should have some notes on how to test this, such as adding another module with a password form on it, so we can manually test as well.

Unassiginng.

Tagging for tests.

Updating version.

I updated merge request for 4.0.x branch with tests and addressed @kristen-pol comments.

@rbrandon, just tested and it works well, but it looks like you're missing the route to the settings form in the last MR.

password_policy.settings:
  path: '/admin/config/security/password-policy/settings'
  defaults:
    _form: '\Drupal\password_policy\Form\SettingsForm'
    _title: 'Password Policy Settings'
  requirements:
    _permission: 'administer site configuration'