feat: add security warning for disabling notifications

[he3als]

Questions

• Did you test your changes or double-check that they work?
• Did you read and follow the Atlas Contribution Guidelines?

Describe your pull request

Adds info and a prompt to the user about the security implications of disabling notification services.

Disabling notifications means all notifications, including system ones.
This includes notifications that notify you about security updates.

This doesn't improve performance.

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Would you like to continue anyways? [Y/N]