Parsing error in UserFieldRole

Problem/Motivation

The UserFieldRole plugin fails to compare correctly for a Role name that is more than a single word.

Steps to reproduce

Create a role: "First edit"
Create a user with this role
Create a "access rule only" and set the handler to user has role, selecting the role created above. Set it to control access to edit.
Add a selection rule which will cause the rule to be selected
Check a content item that would select the rule against the user created and note that it fails with: The 'Current user: Roles (in First edit)' access rule failed..

Proposed resolution

The code in UserFieldRole has this comment

// Roles are stored on the access policy with underscores "_" however they
// are stored in Drupal with a space. We need to replace that underscore
// with the space.

But \Drupal\user\RoleForm has this

 $form['id'] = [
      '#type' => 'machine_name',
      '#default_value' => $entity->id(),
      '#required' => TRUE,
      '#disabled' => !$entity->isNew(),
      '#size' => 30,
      '#maxlength' => 64,
      '#machine_name' => [
        'exists' => ['\Drupal\user\Entity\Role', 'load'],
      ],
    ];

And \Drupal\Core\Render\Element\MachineName::validateMachineName does not allow spaces.

Remaining tasks

Remove the parsing of underscores into space.

User interface changes

API changes

Data model changes