[wpimath] Add ArmFeedforward calculate() overload that takes current and next velocity instead of acceleration (#6540)

Co-authored-by: Tyler Veness <calcmogul@gmail.com>

wpimath/src/main/native/cpp/jni/WPIMathJNI_ArmFeedforward.cpp

@@ -0,0 +1,36 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+#include <jni.h>
+
+#include <wpi/jni_util.h>
+
+#include "edu_wpi_first_math_WPIMathJNI.h"
+#include "frc/controller/ArmFeedforward.h"
+
+using namespace wpi::java;
+
+extern "C" {
+
+/*
+ * Class:     edu_wpi_first_math_WPIMathJNI
+ * Method:    calculate
+ * Signature: (DDDDDDDD)D
+ */
+JNIEXPORT jdouble JNICALL
+Java_edu_wpi_first_math_WPIMathJNI_calculate
+  (JNIEnv* env, jclass, jdouble ks, jdouble kv, jdouble ka, jdouble kg,
+   jdouble currentAngle, jdouble currentVelocity, jdouble nextVelocity,
+   jdouble dt)
+{
+  return frc::ArmFeedforward{units::volt_t{ks}, units::volt_t{kg},
+                             units::unit_t<frc::ArmFeedforward::kv_unit>{kv},
+                             units::unit_t<frc::ArmFeedforward::ka_unit>{ka}}
+      .Calculate(units::radian_t{currentAngle},
+                 units::radians_per_second_t{currentVelocity},
+                 units::radians_per_second_t{nextVelocity}, units::second_t{dt})
+      .value();
+}
+
+}  // extern "C"