[FR] Define PID_DEBUG and extend the PID Calibration menu to add options to Toggle Debug on/off and manually edit PID/apply parameters

[Thinkersbluff]

Since the root cause(s) of the ongoing PID Autotune issues (ref #248) may take a while to resolve, it may be helpful to facilitate the ability of CF users to take more direct control of their PID settings.

According to the Marlin documentation, the M303 function includes a D flag which can toggle the PID_DEBUG reporting function on and off. That might be a helpful addition to the Setup menu. It might also make sense as a toggle button on the Calibrate PID screen.

Since the PID function seems to be generating parameters that don’t work very well, and since factory reset impacts multiple settings, it would be kind to extend the PID screen with a K-factors display and tap to modify capability and maybe display as before/after with the option of reverting or editing or applying the new values. Between M303 and M301, I think you would have all the controls required to implement that degree of flexibility in the UI.

https://marlinfw.org/docs/gcode/M303.html
https://marlinfw.org/docs/gcode/M301.html

[Thinkersbluff]

As a "bonus" for those who love to experiment with optimizing their machine's performance, it would be interesting to add two simple transform options, as alternatives to using the Classic PID values computed by Marlin.

Per the RepRap PID documentation:
"You can transform these "Classic" parameters into the Zeigler-Nichols "Some Overshoot" set with:

Kp=Kp_classic*0.55
Ki=Ki_classic
Kd=Kd_classic*8/3

Or the Z-N "No Overshoot" set:

Kp=Kp_classic/3 
Ki=Ki_classic 
Kd=Kd_classic*8/3"

The "Some Overshoot" option should get to the initial target temperature more quickly, with a bit of ringing before it settles-out.
The "No Overshoot" option should converge gently onto the target, if a little more slowly. For High Temp target settings, that might feel "safer" for some users.