[glass] Field2D: Embed standard field images (#5159)

fieldImages/src/main/native/include/fields/fields.h

@@ -0,0 +1,20 @@
+// 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 <span>
+#include <string_view>
+
+namespace fields {
+
+struct Field {
+  const char* name;
+  std::string_view (*getJson)();
+  std::string_view (*getImage)();
+};
+
+std::span<const Field> GetFields();
+
+}  // namespace fields