[Feature Request] Support thread cutting in Gcode

[Festivejelly]

I've been using the Nano ELS via the gcode function more and more and I think it would be nice to support threading operations through it.

Since we cant set the speed of the spindle in gcode we could instead read the RPM and adjust the feedrate as needed.

So something like G32 Z15.0 would need to work out a base feedrate and adjust that based on the RPM. I guess you did something similar with the automatic threading function on the controller.

Ive made quite a bit of progress on the Ui im building so it would be nice to have this function there.