[commands] Add RepeatCommand (#4009)

Co-authored-by: Starlight220 <53231611+Starlight220@users.noreply.github.com>

wpilibNewCommands/src/main/native/cpp/frc2/command/RepeatCommand.cpp

@@ -0,0 +1,45 @@
+// 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.
+
+#include "frc2/command/RepeatCommand.h"
+
+using namespace frc2;
+
+RepeatCommand::RepeatCommand(std::unique_ptr<Command>&& command) {
+  if (!CommandGroupBase::RequireUngrouped(*command)) {
+    return;
+  }
+  m_command = std::move(command);
+  m_command->SetGrouped(true);
+  AddRequirements(m_command->GetRequirements());
+}
+
+void RepeatCommand::Initialize() {
+  m_command->Initialize();
+}
+
+void RepeatCommand::Execute() {
+  m_command->Execute();
+  if (m_command->IsFinished()) {
+    // restart command
+    m_command->End(false);
+    m_command->Initialize();
+  }
+}
+
+bool RepeatCommand::IsFinished() {
+  return false;
+}
+
+void RepeatCommand::End(bool interrupted) {
+  m_command->End(interrupted);
+}
+
+bool RepeatCommand::RunsWhenDisabled() const {
+  return m_command->RunsWhenDisabled();
+}
+
+RepeatCommand RepeatCommand::Repeat() && {
+  return std::move(*this);
+}