[cmd2] Move .cpp files to subproject source root (#8967)

This matches all of the other subprojects.

Signed-off-by: Zach Harel <zach@zharel.me>

commandsv2/src/main/native/cpp/WrapperCommand.cpp

@@ -0,0 +1,47 @@
+// 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 "wpi/commands2/WrapperCommand.hpp"
+
+#include <utility>
+
+#include "wpi/commands2/Command.hpp"
+
+using namespace wpi::cmd;
+
+WrapperCommand::WrapperCommand(std::unique_ptr<Command>&& command) {
+  CommandScheduler::GetInstance().RequireUngroupedAndUnscheduled(command.get());
+  m_command = std::move(command);
+  m_command->SetComposed(true);
+  // copy the wrapped command's name
+  SetName(m_command->GetName());
+}
+
+void WrapperCommand::Initialize() {
+  m_command->Initialize();
+}
+
+void WrapperCommand::Execute() {
+  m_command->Execute();
+}
+
+bool WrapperCommand::IsFinished() {
+  return m_command->IsFinished();
+}
+
+void WrapperCommand::End(bool interrupted) {
+  m_command->End(interrupted);
+}
+
+bool WrapperCommand::RunsWhenDisabled() const {
+  return m_command->RunsWhenDisabled();
+}
+
+Command::InterruptionBehavior WrapperCommand::GetInterruptionBehavior() const {
+  return m_command->GetInterruptionBehavior();
+}
+
+wpi::util::SmallSet<Subsystem*, 4> WrapperCommand::GetRequirements() const {
+  return m_command->GetRequirements();
+}