Add Debouncer (#3590)

Supersedes #2358 with updates and cleanups.

Closes #2482 and closes #2487 because we shouldn't support both
time-based and count-based debouncing approaches.

Co-authored-by: oblarg <emichaelbarnett@gmail.com>

wpilibj/src/test/java/edu/wpi/first/wpilibj/DebouncerTest.java

@@ -0,0 +1,54 @@
+// 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.
+
+package edu.wpi.first.wpilibj;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import edu.wpi.first.wpilibj.simulation.SimHooks;
+import org.junit.jupiter.api.Test;
+
+public class DebouncerTest {
+  @Test
+  void debounceRisingTest() {
+    var debouncer = new Debouncer(0.02, Debouncer.DebounceType.kRising);
+
+    debouncer.calculate(false);
+    assertFalse(debouncer.calculate(true));
+
+    SimHooks.stepTiming(0.1);
+
+    assertTrue(debouncer.calculate(true));
+  }
+
+  @Test
+  void debounceFallingTest() {
+    var debouncer = new Debouncer(0.02, Debouncer.DebounceType.kFalling);
+
+    debouncer.calculate(true);
+    assertTrue(debouncer.calculate(false));
+
+    SimHooks.stepTiming(0.1);
+
+    assertFalse(debouncer.calculate(false));
+  }
+
+  @Test
+  void debounceBothTest() {
+    var debouncer = new Debouncer(0.02, Debouncer.DebounceType.kBoth);
+
+    debouncer.calculate(false);
+    assertFalse(debouncer.calculate(true));
+
+    SimHooks.stepTiming(0.1);
+
+    assertTrue(debouncer.calculate(true));
+    assertTrue(debouncer.calculate(false));
+
+    SimHooks.stepTiming(0.1);
+
+    assertFalse(debouncer.calculate(false));
+  }
+}