[glass] Add more widgets (#2947)

This adds the following widgets:
- Speed Controller
- Gyroscope
- Command
- Subsystem
- PIDController
- Scheduler

glass/src/lib/native/cpp/other/Subsystem.cpp

@@ -0,0 +1,32 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2020 FIRST. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "glass/other/Subsystem.h"
+
+#include <imgui.h>
+
+#include "glass/Context.h"
+#include "glass/DataSource.h"
+
+using namespace glass;
+
+void glass::DisplaySubsystem(SubsystemModel* m) {
+  if (auto name = m->GetName()) {
+    ImGui::Text("%s", name);
+    ImGui::Separator();
+  }
+  if (m->Exists()) {
+    std::string defaultCommand = m->GetDefaultCommand();
+    std::string currentCommand = m->GetCurrentCommand();
+    ImGui::Text("%s", ("Default Command: " + defaultCommand).c_str());
+    ImGui::Text("%s", ("Current Command: " + currentCommand).c_str());
+  } else {
+    ImGui::PushStyleColor(ImGuiCol_Text, IM_COL32(96, 96, 96, 255));
+    ImGui::Text("Unknown Subsystem");
+    ImGui::PopStyleColor();
+  }
+}