Email handler: Invalid tokens for "Webform submission author"

Problem/Motivation

When selecting Webform submission author display name as the From address for an email handler, the token doesn't get replaced. The same goes for the Webform submission author account name option.

Steps to reproduce

At EmailWebformHandler.php:401

    $other_element_name_options = [
      '[site:name]' => 'Site name',
      '[current-user:display-name]' => 'Current user display name',
      '[current-user:account-name]' => 'Current user account name',
      '[webform:author:display-name]' => 'Webform author display name',
      '[webform:author:account-name]' => 'Webform author account name',
      '[webform_submission:account:display-name]' => 'Webform submission author display name',
      '[webform_submission:account:account-name]' => 'Webform submission author account name',
    ];

However, [webform_submission:account:?] is not a valid token.

Proposed resolution

It should be "user" instead of "account" for those two tokens:

    $other_element_name_options = [
      '[site:name]' => 'Site name',
      '[current-user:display-name]' => 'Current user display name',
      '[current-user:account-name]' => 'Current user account name',
      '[webform:author:display-name]' => 'Webform author display name',
      '[webform:author:account-name]' => 'Webform author account name',
      '[webform_submission:user:display-name]' => 'Webform submission author display name',
      '[webform_submission:user:account-name]' => 'Webform submission author account name',
    ];

Remaining tasks

User interface changes

API changes

Data model changes