Add Units Utility class for Java (#1829)

Units conversion class to convert between commonly used units.

Co-Authored-By: Austin Shalit <austinshalit@gmail.com>

wpilibj/src/test/java/edu/wpi/first/wpilibj/util/UnitsTest.java

@@ -0,0 +1,60 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2019 FIRST. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+package edu.wpi.first.wpilibj.util;
+
+import org.junit.jupiter.api.Test;
+
+import edu.wpi.first.wpilibj.UtilityClassTest;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class UnitsTest extends UtilityClassTest<Units> {
+  UnitsTest() {
+    super(Units.class);
+  }
+
+  @Test
+  void metersToFeetTest() {
+    assertEquals(3.28, Units.metersToFeet(1), 1e-2);
+  }
+
+  @Test
+  void feetToMetersTest() {
+    assertEquals(0.30, Units.feetToMeters(1), 1e-2);
+  }
+
+  @Test
+  void metersToInchesTest() {
+    assertEquals(39.37, Units.metersToInches(1), 1e-2);
+  }
+
+  @Test
+  void inchesToMetersTest() {
+    assertEquals(0.0254, Units.inchesToMeters(1), 1e-3);
+  }
+
+  @Test
+  void degreesToRadiansTest() {
+    assertEquals(0.017, Units.degreesToRadians(1), 1e-3);
+  }
+
+  @Test
+  void radiansToDegreesTest() {
+    assertEquals(114.59, Units.radiansToDegrees(2), 1e-2);
+  }
+
+  @Test
+  void rotationsPerMinuteToRadiansPerSecondTest() {
+    assertEquals(6.28, Units.rotationsPerMinuteToRadiansPerSecond(60), 1e-2);
+  }
+
+  @Test
+  void radiansPerSecondToRotationsPerMinute() {
+    assertEquals(76.39, Units.radiansPerSecondToRotationsPerMinute(8), 1e-2);
+  }
+}