[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/main/native/include/frc2/command/SelectCommand.h

@@ -16,7 +16,6 @@
 #include <utility>
 #include <vector>
 
-#include <wpi/deprecated.h>
 #include <wpi/sendable/SendableBuilder.h>
 
 #include "frc2/command/CommandBase.h"
@@ -95,17 +94,6 @@ class SelectCommand : public CommandHelper<CommandBase, SelectCommand<Key>> {
   // Prevent template expansion from emulating copy ctor
   SelectCommand(SelectCommand&) = delete;
 
-  /**
-   * Creates a new selectcommand.
-   *
-   * @param toRun a supplier providing the command to run
-   * @deprecated Replace with {@link ProxyCommand},
-   * composing multiple of them in a {@link ParallelRaceGroup} if needed.
-   */
-  WPI_DEPRECATED("Replace with ProxyCommand")
-  explicit SelectCommand(std::function<Command*()> toRun)
-      : m_toRun{std::move(toRun)} {}
-
   SelectCommand(SelectCommand&& other) = default;
 
   void Initialize() override;
@@ -147,7 +135,6 @@ class SelectCommand : public CommandHelper<CommandBase, SelectCommand<Key>> {
  private:
   std::unordered_map<Key, std::unique_ptr<Command>> m_commands;
   std::function<Key()> m_selector;
-  std::function<Command*()> m_toRun;
   Command* m_selectedCommand;
   bool m_runsWhenDisabled = true;
   Command::InterruptionBehavior m_interruptBehavior{
@@ -156,16 +143,12 @@ class SelectCommand : public CommandHelper<CommandBase, SelectCommand<Key>> {
 
 template <typename T>
 void SelectCommand<T>::Initialize() {
-  if (m_selector) {
-    auto find = m_commands.find(m_selector());
-    if (find == m_commands.end()) {
-      m_selectedCommand = new PrintCommand(
-          "SelectCommand selector value does not correspond to any command!");
-      return;
-    }
-    m_selectedCommand = find->second.get();
+  auto find = m_commands.find(m_selector());
+  if (find == m_commands.end()) {
+    m_selectedCommand = new PrintCommand(
+        "SelectCommand selector value does not correspond to any command!");
   } else {
-    m_selectedCommand = m_toRun();
+    m_selectedCommand = find->second.get();
   }
   m_selectedCommand->Initialize();
 }