This implements de/serialization for the types that aren't templated (SwerveDriveKinematics) in C++ or where there is no trivial way to go round-trip (Splines) for the messages.
RKDP is strictly better in terms of accuracy per unit of work. We used
RKF45 for sim physics in the 2021 season, but we transitioned to RKDP
before the 2022 season.
* Replace Matrix<> with Vector<> where vectors are explicitly intended.
I found these via `rg "Eigen::Matrix<double, \w+, 1>"`.
* Pass all Eigen matrices by const reference. I found these via `rg
"\(Eigen"` on main (the initializer list constructors make more false
positives).
* Replace MakeMatrix() and operator<< usage with initializer list
constructors. I found these via `rg MakeMatrix` and `rg "<<"`
respectively.
* Deprecate MakeMatrix()
* Rename Butcher tableau sections in NumericalIntegration such that
top-left is c, top-right is A, and bottom-right is b
* Move edu.wpi.first.math.Discretization to
edu.wpi.first.math.system.Discretization
* Sort Java Discretization to match C++ function order
* Add tests for Java Discretization
* Required adding Runge-Kutta time-varying impl to tests
* Move C++ Runge-Kutta time-varying impl to tests only
* Users don't need it
Also refactored RKF45 implementation to match the new style, which is
easier to read.
The tests were switched from RKF45 to RKDP since it's more accurate.
This helps reduce compilation overhead. I tried slimming down includes
of <Eigen/QR>, but the householderQr() function we use from there
requires including dependency headers from Eigen that don't fit with
lexographic ordering. It didn't seem worth the effort to work around.
This won't affect user code at all since all the Eigen feature usage
here is internal only; users generally only need <Eigen/Core>.
