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FLASHING.md says how to take a newer version of the colleague's tree (copy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/vanetza/asn1/tests/its.cpp

@@ -0,0 +1,72 @@
+#include <gtest/gtest.h>
+#include <vanetza/asn1/asn1c_wrapper.hpp>
+#include <vanetza/asn1/cam.hpp>
+#include <vanetza/asn1/denm.hpp>
+#include <vanetza/asn1/mapem.hpp>
+#include <vanetza/asn1/spatem.hpp>
+#include <vanetza/asn1/ssem.hpp>
+#include <vanetza/asn1/srem.hpp>
+#include <vanetza/asn1/ivim.hpp>
+#include <vanetza/asn1/its/TimestampIts.h>
+
+using namespace vanetza;
+
+TEST(ItsAsn1, max_timestamp_roundtrip)
+{
+    const std::int64_t max_timestamp = 4398046511103;
+    asn1::asn1c_wrapper<TimestampIts_t> tx { asn_DEF_TimestampIts };
+    asn_imax2INTEGER(&*tx, max_timestamp);
+    auto buffer = tx.encode();
+    EXPECT_EQ(6, buffer.size());
+    asn1::asn1c_wrapper<TimestampIts_t> rx { asn_DEF_TimestampIts };
+    EXPECT_TRUE(rx.decode(buffer));
+    std::int64_t rx_timestamp = 0;
+    asn_INTEGER2imax(&*tx, &rx_timestamp);
+    EXPECT_EQ(rx_timestamp, max_timestamp);
+}
+
+TEST(ItsAsn1, encode_denm)
+{
+    asn1::Denm denm;
+    EXPECT_EQ(0, asn_uint642INTEGER(&denm->denm.management.detectionTime, TimestampIts_utcStartOf2004));
+    EXPECT_EQ(0, asn_uint642INTEGER(&denm->denm.management.referenceTime, TimestampIts_utcStartOf2004));
+    EXPECT_TRUE(denm.validate());
+    vanetza::ByteBuffer buf = denm.encode();
+    EXPECT_EQ(40, buf.size());
+}
+
+TEST(ItsAsn1, create_cam)
+{
+    asn1::Cam cam;
+}
+
+TEST(ItsAsn1, create_denm)
+{
+    asn1::Denm denm;
+}
+
+TEST(ItsAsn1, create_mapem)
+{
+    asn1::Mapem mapem;
+}
+
+TEST(ItsAsn1, create_spatem)
+{
+    asn1::Spatem spatem;
+}
+
+TEST(ItsAsn1, create_srem)
+{
+    asn1::Srem srem;
+}
+
+TEST(ItsAsn1, create_ssem)
+{
+    asn1::Ssem ssem;
+}
+
+TEST(ItsAsn1, create_ivim)
+{
+    asn1::Ivim ivim;
+}
+