Hide values in the Admin Panel

[soup-bowl]

Describe your desired feature

Request from pablor21 on the forums:

When using environment variables or setting the SMTP_* credentials in wp-config.php the values are displayed, albeit greyed out, in the WordPress Simple SMTP settings page of WP Admin.

Would it be possible to mask or simply not display any credentials/settings in WP Admin? The reason for setting the credentials as environment variables is to add extra security. These values should not be displayed (or maybe have an option to display values or not).