Add a validation to cheak a tenant email against `End user email address`

@yas, please review this patch. I've added validation to make sure the user does not choose values that are the same as the drupal_enduser_email and drupal_enduser_username

@baldwinlouie

Thank you for the fix. I posted my comment to use a guard clause.

Thanks

@yas, please review.

@baldwinlouie

Thank you for the update. Can you please take a look at phpcs errors at https://git.drupalcode.org/project/facade/-/jobs/687494? Thanks!

@yas, I've fixed the PHPCS errors.

@baldwinlouie

Thank you for the update. I posted my comment. Thanks!

@baldwinlouie

Thank you for the update. It looks good to me now. I'll merge the patch to 1.0.x, and close this issue as Fixed.

Automatically closed - issue fixed for 2 weeks with no activity.