[commands] Remove deprecated classes and functions (#5409)

Removes:
- PerpetualCommand
- Command.perpetually()
- CommandGroupBase
- Command.IsGrouped() (C++ only)
- Command.SetGrouped() (C++ only)
- Command.withInterrupt()
- ProxyScheduleCommand
- Button
- InternalButton, JoystickButton, NetworkButton and POVButton now subclass Trigger
- Old style Trigger functions:
    - Trigger.whenActive
    - Trigger.whileActiveOnce
    - Trigger.whileActiveContinuous
    - Trigger.whenInactive
    - Trigger.toggleWhenActive
    - Trigger.cancelWhenActive
- CommandScheduler.clearButtons()
- CommandScheduler.addButtons() (Java only)
- Command supplier constructor of SelectCommand

wpilibNewCommands/src/test/java/edu/wpi/first/wpilibj2/command/CommandDecoratorTest.java

@@ -200,23 +200,6 @@ class CommandDecoratorTest extends CommandTestBase {
     }
   }
 
-  @SuppressWarnings("removal") // Command.perpetually()
-  @Test
-  void perpetuallyTest() {
-    try (CommandScheduler scheduler = new CommandScheduler()) {
-      Command command = new InstantCommand();
-
-      Command perpetual = command.perpetually();
-
-      scheduler.schedule(perpetual);
-      scheduler.run();
-      scheduler.run();
-      scheduler.run();
-
-      assertTrue(scheduler.isScheduled(perpetual));
-    }
-  }
-
   @Test
   void unlessTest() {
     try (CommandScheduler scheduler = new CommandScheduler()) {

wpilibNewCommands/src/test/java/edu/wpi/first/wpilibj2/command/PerpetualCommandTest.java

@@ -1,24 +0,0 @@
-// 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.wpilibj2.command;
-
-import static org.junit.jupiter.api.Assertions.assertTrue;
-
-import org.junit.jupiter.api.Test;
-
-class PerpetualCommandTest extends CommandTestBase {
-  @SuppressWarnings("removal") // PerpetualCommand
-  @Test
-  void perpetualCommandScheduleTest() {
-    try (CommandScheduler scheduler = new CommandScheduler()) {
-      PerpetualCommand command = new PerpetualCommand(new InstantCommand());
-
-      scheduler.schedule(command);
-      scheduler.run();
-
-      assertTrue(scheduler.isScheduled(command));
-    }
-  }
-}

wpilibNewCommands/src/test/java/edu/wpi/first/wpilibj2/command/button/TriggerTest.java

@@ -194,34 +194,6 @@ class TriggerTest extends CommandTestBase {
     assertEquals(1, endCounter.get());
   }
 
-  // Binding runnables directly is deprecated -- users should create the command manually
-  @SuppressWarnings("deprecation")
-  @Test
-  void runnableBindingTest() {
-    InternalButton buttonWhenActive = new InternalButton();
-    InternalButton buttonWhileActiveContinuous = new InternalButton();
-    InternalButton buttonWhenInactive = new InternalButton();
-
-    buttonWhenActive.setPressed(false);
-    buttonWhileActiveContinuous.setPressed(true);
-    buttonWhenInactive.setPressed(true);
-
-    AtomicInteger counter = new AtomicInteger(0);
-
-    buttonWhenActive.whenPressed(counter::incrementAndGet);
-    buttonWhileActiveContinuous.whileActiveContinuous(counter::incrementAndGet);
-    buttonWhenInactive.whenInactive(counter::incrementAndGet);
-
-    CommandScheduler scheduler = CommandScheduler.getInstance();
-
-    scheduler.run();
-    buttonWhenActive.setPressed(true);
-    buttonWhenInactive.setPressed(false);
-    scheduler.run();
-
-    assertEquals(counter.get(), 4);
-  }
-
   @Test
   void triggerCompositionTest() {
     InternalButton button1 = new InternalButton();