drush migrate:fields-source vs. strict_types

[nevergone]

Describe the bug
Drupal migration source plugins return translated text (TranslatableMarkup) in field descriptions. See: https://api.drupal.org/api/drupal/core%21modules%21user%21src%21Plugin%21migrate%21source%21d7%21User.php/function/User%3A%3Afields/10
The strip_tags() PHP function given string in \Drush\Commands\core\MigrateRunnerCommands::fieldsSource() method.

Automatic type conversion cannot be used because of declare(strict_types=1);

To Reproduce
Load old Drupal-dump (for ex. Drupal7) and probe drush mfs d7_user command.

System Configuration

Q	A
Drush version?	12.x/13.x
Drupal version?	10.x/
PHP version	8.x/
OS?	Linux

Additional information
Please cherry-pick for 12.x branch.

[claudiu-cristea]

@nevergone we need a PR

[nevergone]

#6015

[nevergone]

Thanks.