[FR] Add host/serial print options to special menu

[mlewis-everley]

Description

On vanilla marlin, using standard screens (not the custom anycubic ones) you can add "Start Host Print" and "Stop Host Print" buttons to the UI. I believe these buttons use the M118 (serial print: https://marlinfw.org/docs/gcode/M118.html) GCODE to send an action to a connected host.

It would be awesome if the special print menu had something similar, so if you are using OctoPrint and you notice a fail, or want to run the same print again, you don't have to login via your computer/phone/tablet to perform this fairly simple action.

Feature Workflow

1. Printer is connected to OctoPrint (maybe other hosts) via USB.
2. If not printing, open Print > Special Menu and browse to "Start Host Print"
3. If already printing, navigate to Print > Special Menu and choose "Stop Host Print"
4. Printer sendsM118 command to OctoPrint/Host?

Additional Information

These buttons could be at the top level of the Special Menu, or under "Host Actions" maybe?

Also, I assume that the Anycubic UI cannot determine if a print is currently running and change the buttons accordingly? If so I guess all host actions could be loaded and it is up to the user to apply some common sense?

Thoughts?