Shove kicad2step into pcbnew itself with a new cli

thirdparty/argparse/samples/optional_flag_argument.cpp

@@ -0,0 +1,22 @@
+#include <argparse/argparse.hpp>
+
+int main(int argc, char *argv[]) {
+  argparse::ArgumentParser program("test");
+
+  program.add_argument("--verbose")
+      .help("increase output verbosity")
+      .default_value(false)
+      .implicit_value(true);
+
+  try {
+    program.parse_args(argc, argv);
+  } catch (const std::runtime_error &err) {
+    std::cerr << err.what() << std::endl;
+    std::cerr << program;
+    std::exit(1);
+  }
+
+  if (program["--verbose"] == true) {
+    std::cout << "Verbosity enabled" << std::endl;
+  }
+}