Feature request: Virtual SD card printing

[maartenvang]

Using the virtual SD card is a great way to avoid a lot of issues regarding the serial communication overhead. I have found that printing via virtual SD card works perfectly every time, while printing through octoprint directly can lead to the printer stalling while trying to keep up.

I've read that you can print from SD using klipper gcode commands. I thought it may be a good idea to be able to press print in octoprint and have it print through virtual SD instead of serial.