Tail precomp improvements

[rotorflight]

UPDATED on 8/1/2025

This PR also includes the RPM filter refactoring from #194.

There is a hack for using the old dynamic precomp MSP parameters for the new inertia precomp.
Thus the inertia settings can be changed in the Configurator with the old dynamic precomp parameters.

[rotorflight]

Parameters

set yaw_inertia_precomp_gain = <0-100>

Amount of main rotor inertia.
Start with 10. Increment by 5.

set yaw_inertia_precomp_cutoff = <1-100>

Time of inertia dissipation, unit is Hz.
Presumably 2-100 range is working.
Try 20 (~50ms) to start with.

Removed parameters

yaw_collective_dynamic_gain
yaw_collective_dynamic_decay

[rotorflight]

A note on the inertia precomp.

It is doing something only if the headspeed changes. If the motor/esc/governor were ideal, and the headspeed would stay constant, the estimated coll->yaw precomp would be correct. But, if the headspeed drops, the estimated coll->yaw precomp is too much, and needs to be lowered. This is what the inertia precomp does, it adjusts the yaw precomp based on the headspeed change speed. The RPM drop speed indicates how much torque is "missing" from keeping the RPM constant, and thus how much the yaw precomp must be reduced.

To tune it, first tune the coll->precomp with a full battery, and avoid doing tests that drops the headspeed. Then tune the inertia precomp so that the moves that actually drops the headspeed won't affect the tail. This is escpecially visible when the battery is nearly flat, and the throttle saturates at 100%.

A flat battery can be simulated by setting the Max throttle in the governor to a lower value, like 90% or 85%.