[wpimath] Move RobotDriveBase::ApplyDeadband() to MathUtil (#3529)

It's a useful function outside of the drive classes.

For backwards compatibility, deprecate (rather than remove) RobotDriveBase.applyDeadband()

wpilibjExamples/src/main/java/edu/wpi/first/wpilibj/examples/swervebot/Robot.java

@@ -4,6 +4,7 @@
 
 package edu.wpi.first.wpilibj.examples.swervebot;
 
+import edu.wpi.first.math.MathUtil;
 import edu.wpi.first.math.filter.SlewRateLimiter;
 import edu.wpi.first.wpilibj.TimedRobot;
 import edu.wpi.first.wpilibj.XboxController;
@@ -31,18 +32,24 @@ public class Robot extends TimedRobot {
   private void driveWithJoystick(boolean fieldRelative) {
     // Get the x speed. We are inverting this because Xbox controllers return
     // negative values when we push forward.
-    final var xSpeed = -m_xspeedLimiter.calculate(m_controller.getLeftY()) * Drivetrain.kMaxSpeed;
+    final var xSpeed =
+        -m_xspeedLimiter.calculate(MathUtil.applyDeadband(m_controller.getLeftY(), 0.02))
+            * Drivetrain.kMaxSpeed;
 
     // Get the y speed or sideways/strafe speed. We are inverting this because
     // we want a positive value when we pull to the left. Xbox controllers
     // return positive values when you pull to the right by default.
-    final var ySpeed = -m_yspeedLimiter.calculate(m_controller.getLeftX()) * Drivetrain.kMaxSpeed;
+    final var ySpeed =
+        -m_yspeedLimiter.calculate(MathUtil.applyDeadband(m_controller.getLeftX(), 0.02))
+            * Drivetrain.kMaxSpeed;
 
     // Get the rate of angular rotation. We are inverting this because we want a
     // positive value when we pull to the left (remember, CCW is positive in
     // mathematics). Xbox controllers return positive values when you pull to
     // the right by default.
-    final var rot = -m_rotLimiter.calculate(m_controller.getRightX()) * Drivetrain.kMaxAngularSpeed;
+    final var rot =
+        -m_rotLimiter.calculate(MathUtil.applyDeadband(m_controller.getRightX(), 0.02))
+            * Drivetrain.kMaxAngularSpeed;
 
     m_swerve.drive(xSpeed, ySpeed, rot, fieldRelative);
   }