Prevent guest authors from logging in, disable account related functionality

[johnbillion]

A user with a role of Guest Author should not be able to log in at all.

• Password should be set to a long random password when a guest author is created
• Logging in should be denied at the authentication level
  • Logging in at wp-login.php
  • WordPress core application passwords
  • REST API Basic Auth
  • XML-RPC
• Ensure the guest author does not get sent an email when their account is created
• Disable password reset functionality for the user

The Disable Accounts plugin should do most of what we need. If there's anything missing, let's send fixes upstream to that plugin too.

[ntwb]

The Disable Accounts plugin should do most of what we need. If there's anything missing, let's send fixes upstream to that plugin too.

FYI: This plugin is included in the `altis/security module as of v9

• https://docs.altis-dxp.com/security/disable-accounts/