Add a check for Feeds import (Feeds integration)

Problem/Motivation

If a site builder uses Feeds Import to import users on comments, it will trigger Comment Notify to send emails to all of those users, which can result in situations like Google SMTP servers banning the site for spam.

This can be avoided by unchecking the "Default subscribe to mail" in the Comment Notify settings, but that is not apparent to everyone.

Proposed resolution

Add a default check for Feeds Import.

Remaining tasks

1. ❌ Refine and finalize solution
2. ❌ Implement solution
3. ❌ Test