Keep the colleague's microbu-esp32c5 tree in this repository

obu-firmware builds against vanetza-idf from microbu-esp32c5/external, but
that tree was gitignored, so a clone of this repository could not build the
firmware it ships. It is now committed here as ordinary files in its own
folder, microbu-esp32c5/: the colleague's commit cf4b99f plus the V2X2MAP
bridge's signature verification (--trust) used on the bench. Nothing is
fetched from or pushed to the colleague's repository; this repository and
its remotes carry everything. The folder's own .gitignore keeps build output,
downloaded components and private key material out, as it did there; the
committed file set is identical to that repository's tracked files.

The ESP32-C5 is still flashed from obu-firmware/, which only takes
vanetza-idf from microbu-esp32c5/, so the two stay separate folders.
FLASHING.md says how to take a newer version of the colleague's tree (copy
it over the folder, rebuild, test, commit).

microbu-esp32c5/external/vanetza-idf/tools/benchmark/options.cpp

@@ -0,0 +1,63 @@
+#include "cases/security/signing.hpp"
+#include "cases/security/validation.hpp"
+#include "options.hpp"
+#include <boost/program_options.hpp>
+#include <iostream>
+#include <memory>
+
+namespace po = boost::program_options;
+
+std::unique_ptr<Case> parse_options(int argc, const char *argv[])
+{
+    po::options_description global("Global options");
+    global.add_options()
+        ("case", po::value<std::string>(), "Case to execute.")
+        ("subargs", po::value<std::vector<std::string>>(), "Arguments for case.");
+
+    po::positional_options_description pos;
+    pos.add("case", 1);
+    pos.add("subargs", -1);
+
+    po::variables_map vm;
+
+    po::parsed_options parsed = po::command_line_parser(argc, argv)
+        .options(global)
+        .positional(pos)
+        .allow_unregistered()
+        .run();
+
+    po::store(parsed, vm);
+    po::notify(vm);
+
+    std::string available_commands = "Available cases: security-validation, security-signing";
+
+    if (!vm.count("case")) {
+        std::cerr << global << std::endl;
+        std::cerr << available_commands << std::endl;
+
+        return nullptr;
+    }
+
+    std::string name = vm["case"].as<std::string>();
+    std::unique_ptr<Case> instance;
+
+    if (name == "--help") {
+        std::cerr << global << std::endl;
+        std::cerr << available_commands << std::endl;
+    } else if (name == "security-signing") {
+        instance.reset(new SecuritySigningCase());
+    } else if (name == "security-validation") {
+        instance.reset(new SecurityValidationCase());
+    } else {
+        throw std::runtime_error("Unknown benchmark case.");
+    }
+
+    std::vector<std::string> opts = po::collect_unrecognized(parsed.options, po::include_positional);
+    opts.erase(opts.begin());
+
+    if (!instance->parse(opts)) {
+        return nullptr;
+    }
+
+    return instance;
+}