[glass, wpilib] Rewrite Mechanism2d (#3281)

Substantially improves Mechanism2d by moving it to NetworkTables and adding
a robot API to create the mechanism elements, instead of requiring a JSON file.

Co-authored-by: Peter Johnson <johnson.peter@gmail.com>

wpilibc/src/main/native/include/frc/simulation/Mechanism2D.h

@@ -1,42 +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.
-
-#pragma once
-
-#include <map>
-#include <string>
-
-#include <hal/SimDevice.h>
-#include <wpi/StringMap.h>
-
-#include "frc/geometry/Pose2d.h"
-#include "frc/geometry/Rotation2d.h"
-
-namespace frc {
-class Mechanism2D {
- public:
-  Mechanism2D();
-
-  /**
-   * Set/Create the angle of a ligament
-   *
-   * @param ligamentPath json path to the ligament
-   * @param angle to set the ligament
-   */
-  void SetLigamentAngle(const wpi::Twine& ligamentPath, float angle);
-
-  /**
-   * Set/Create the length of a ligament
-   *
-   * @param ligamentPath json path to the ligament
-   * @param length to set the ligament
-   */
-  void SetLigamentLength(const wpi::Twine& ligamentPath, float length);
-
- private:
-  wpi::StringMap<hal::SimDouble> createdItems;
-  hal::SimDevice m_device;
-};
-
-}  // namespace frc