[wpimath] Make SimpleMotorFeedforward only support discrete feedforward (#6647)

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

wpilibcExamples/src/main/cpp/examples/ElevatorExponentialProfile/cpp/Robot.cpp

@@ -40,8 +40,7 @@ class Robot : public frc::TimedRobot {
     m_motor.SetSetpoint(
         ExampleSmartMotorController::PIDMode::kPosition,
         m_setpoint.position.value(),
-        m_feedforward.Calculate(m_setpoint.velocity, next.velocity, kDt) /
-            12_V);
+        m_feedforward.Calculate(m_setpoint.velocity, next.velocity) / 12_V);
 
     m_setpoint = next;
   }

wpilibcExamples/src/main/cpp/examples/EventLoop/cpp/Robot.cpp

@@ -54,9 +54,10 @@ class Robot : public frc::TimedRobot {
         // accelerate the shooter wheel
         .IfHigh([&shooter = m_shooter, &controller = m_controller, &ff = m_ff,
                  &encoder = m_shooterEncoder] {
-          shooter.SetVoltage(units::volt_t{controller.Calculate(
-                                 encoder.GetRate(), SHOT_VELOCITY.value())} +
-                             ff.Calculate(SHOT_VELOCITY));
+          shooter.SetVoltage(
+              units::volt_t{controller.Calculate(encoder.GetRate(),
+                                                 SHOT_VELOCITY.value())} +
+              ff.Calculate(units::radians_per_second_t{SHOT_VELOCITY}));
         });
     // if not, stop
     (!shootTrigger).IfHigh([&shooter = m_shooter] { shooter.Set(0.0); });

wpilibcExamples/src/main/cpp/examples/FlywheelBangBangController/cpp/Robot.cpp

@@ -11,6 +11,7 @@
 #include <frc/simulation/EncoderSim.h>
 #include <frc/simulation/FlywheelSim.h>
 #include <frc/smartdashboard/SmartDashboard.h>
+#include <frc/system/plant/LinearSystemId.h>
 #include <units/moment_of_inertia.h>
 
 /**

wpilibcExamples/src/main/cpp/examples/Frisbeebot/cpp/subsystems/ShooterSubsystem.cpp

@@ -5,6 +5,7 @@
 #include "subsystems/ShooterSubsystem.h"
 
 #include <frc/controller/PIDController.h>
+#include <units/angular_velocity.h>
 
 #include "Constants.h"