Refactor Feedforward Angle and RC Smoothing - mashup of 12578 and 12594 (#12605)

Refactor Feedforward Angle and RC Smoothing - mashup of 12578 and 12594 (#12605)

* Refactor Feedforward Angle and RC Smoothing

* update rc_smoothing at regular intervals

* add Earth Ref to OSD, update pid and rate PG

* Initialise filters correctly

* refactoring to improve performance

* Save 24 cycles in Horizon calculations, other optimisations

At a cost of 40 bytes

* save 25 cycles and 330 bytes in rc_smoothing

* feedforward max rate improvements

* typo fix

* Karatebrot's review suggestions  part one

* Karatebrot's excellent suggestions part 2

* more efficient if we calculate inverse at init time

Co-Authored-By: Jan Post <post@stud.tu-darmstadt.de>
* Horizon delay, to ease it in when returning sticks to centre

* fix unit tests after horizon changes

Co-Authored-By: 4712 <4712@users.noreply.github.com>
* horizon_delay_ms, default 500

* fix unit test for feedforward from setpointDelta

* Final optimisations - thanks @Karatebrot for your advice

* increase horizon level strength default to 75 now we have the delay

* restore Makefile value which allowed local make test on mac

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Co-authored-by: Jan Post <post@stud.tu-darmstadt.de>
Co-authored-by: 4712 <4712@users.noreply.github.com>