Allow setting admin user notification email receiver

[Judx]

Description (*)

This PR allows setting receiver email to "New Admin User Create Notification". Default is that email is sent to store general email address. In some cases it is necessary to allow changing the notification receiver.

Related Pull Requests

Depends on and includes changes from https://github.com/OpenMage/magento-lts/pull/3721

Fixed Issues (if relevant)

No.

Manual testing scenarios (*)

1. Pull changes.
2. Find and set email address in: System -> Admin -> Security -> Notification Email Receiver
3. Create new admin user and see that the notification email is received by the specified address.

Questions or comments

Contribution checklist (*)

• [x] Pull request has a meaningful description of its purpose
• [x] All commits are accompanied by meaningful commit messages
• [x] All automated tests passed successfully (all builds are green)
• [x] Add yourself to contributors list