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FLASHING.md says how to take a newer version of the colleague's tree (copy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/cases/security/base.cpp

@@ -0,0 +1,49 @@
+#include "base.hpp"
+#include "vanetza/security/v2/sign_service.hpp"
+#include "vanetza/security/straight_verify_service.hpp"
+#include <boost/date_time/posix_time/posix_time.hpp>
+#include <iostream>
+
+using namespace vanetza;
+using namespace vanetza::security;
+
+SecurityBaseCase::SecurityBaseCase() :
+    runtime(Clock::at(boost::posix_time::microsec_clock::universal_time())),
+    crypto_backend(create_backend("default")),
+    certificate_cache(runtime),
+    certificate_provider(runtime),
+    certificate_validator(*crypto_backend, certificate_cache, trust_store),
+    sign_header_policy(runtime, positioning),
+    security_entity(create_sign_service(), create_verify_service())
+{
+    // nothing to do
+}
+
+void SecurityBaseCase::prepare()
+{
+    PositionFix position;
+    position.latitude = 49.014420 * units::degree;
+    position.longitude = 8.404417 * units::degree;
+    position.confidence.semi_major = 25.0 * units::si::meter;
+    position.confidence.semi_minor = 25.0 * units::si::meter;
+    assert(position.confidence);
+
+    positioning.position_fix(position);
+}
+
+std::unique_ptr<SignService> SecurityBaseCase::create_sign_service()
+{
+    return std::unique_ptr<SignService> {
+        new v2::StraightSignService(certificate_provider, *crypto_backend, sign_header_policy)
+    };
+}
+
+std::unique_ptr<VerifyService> SecurityBaseCase::create_verify_service()
+{
+    std::unique_ptr<StraightVerifyService> verify_service { new StraightVerifyService(runtime, *crypto_backend, positioning) };
+    verify_service->use_certificate_cache(&certificate_cache);
+    verify_service->use_certificate_provider(&certificate_provider);
+    verify_service->use_certificate_validator(&certificate_validator);
+    verify_service->use_sign_header_policy(&sign_header_policy);
+    return verify_service;
+}