[commands] Merge CommandBase into Command and SubsystemBase into Subsystem (#5392)

Moves all CommandBase functionality into Command and deprecates CommandBase for removal.
Moves all SubsystemBase functionality into Subsystem and deprecates SubsystemBase for removal.
Adds a function to CommandScheduler to remove all registered Subsystems.

wpilibNewCommands/src/main/native/include/frc2/command/Subsystem.h

@@ -5,8 +5,11 @@
 #pragma once
 
 #include <concepts>
+#include <string>
 #include <utility>
 
+#include <wpi/sendable/Sendable.h>
+
 #include "frc2/command/CommandScheduler.h"
 
 namespace frc2 {
@@ -23,22 +26,19 @@ class CommandPtr;
  * subsystem should generally remain encapsulated and not be shared by other
  * parts of the robot.
  *
- * <p>Subsystems must be registered with the scheduler with the
+ * <p>Subsystems are automatically registered with the scheduler with the
  * CommandScheduler.RegisterSubsystem() method in order for the
- * Periodic() method to be called.  It is recommended that this method be called
- * from the constructor of users' Subsystem implementations.  The
- * SubsystemBase class offers a simple base for user implementations
- * that handles this.
+ * Periodic() method to be called.
  *
  * This class is provided by the NewCommands VendorDep
  *
  * @see Command
  * @see CommandScheduler
- * @see SubsystemBase
  */
-class Subsystem {
+class Subsystem : public wpi::Sendable, public wpi::SendableHelper<Subsystem> {
  public:
-  virtual ~Subsystem();
+  ~Subsystem() override;
+
   /**
    * This method is called periodically by the CommandScheduler.  Useful for
    * updating subsystem-specific state that you don't want to offload to a
@@ -110,6 +110,43 @@ class Subsystem {
    */
   void Register();
 
+  /**
+   * Gets the name of this Subsystem.
+   *
+   * @return Name
+   */
+  std::string GetName() const;
+
+  /**
+   * Sets the name of this Subsystem.
+   *
+   * @param name name
+   */
+  void SetName(std::string_view name);
+
+  /**
+   * Gets the subsystem name of this Subsystem.
+   *
+   * @return Subsystem name
+   */
+  std::string GetSubsystem() const;
+
+  /**
+   * Sets the subsystem name of this Subsystem.
+   *
+   * @param name subsystem name
+   */
+  void SetSubsystem(std::string_view name);
+
+  /**
+   * Associate a Sendable with this Subsystem.
+   * Also update the child's name.
+   *
+   * @param name name to give child
+   * @param child sendable
+   */
+  void AddChild(std::string name, wpi::Sendable* child);
+
   /**
    * Constructs a command that runs an action once and finishes. Requires this
    * subsystem.
@@ -147,5 +184,10 @@ class Subsystem {
    */
   [[nodiscard]]
   CommandPtr RunEnd(std::function<void()> run, std::function<void()> end);
+
+  void InitSendable(wpi::SendableBuilder& builder) override;
+
+ protected:
+  Subsystem();
 };
 }  // namespace frc2