API/Automation: Add SYSTEM comments to a ticket

As discussed in ##26246062, please consider adding a way to add custom SYSTEM level comments to a ticket, on-demand, through both the API & automation rules. These would be useful as we integrate more of our helpdesk into custom workflows with our other tools and applications. The alternative would be to write "for tech only" comments to the ticket as the user authenticated with the API, which then adds them as a subscriber and becomes a confusing mess. Looking for a much more elegant solution.