Feature Request: Automatically shut down hotend fan during input shaper

[jaakops]

https://github.com/MRX8024/motors-sync/blob/main/wiki/EN.md

From above macro consider adding the following portion to [adxl345] or [resonance_tester], wherever it applies.

#head_fan:
#    Toolhead fan, which will be turned off during sync to eliminate noise.
#    This is convenient when the fan has a low temp target and is often
#    turned on, for example in thermal chamber.

Why?
Do not turn on the hotend heating during synchronization. Working the fan (in general, any fan in the printer) can interfere with correct and more accurate measurement.

[The-Original-Reth]

I think it might be better to add this as an option in [reasonance_testeror] as some may prefer to test the effect of the hotend fan and part cooling fan effect upon resonance.

Something like
fan_off: fan, part_cooling fan, mcu_fan

This may allow one to decide which fans to turn off and which to keep on

[rogerlz]

I prefer to add a warning saying that a fan is running when the user starts the testing. Turning the hotend fan off and bypassing the heater control could be dangerous.