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FLASHING.md says how to take a newer version of the colleague's tree (copy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

@@ -0,0 +1,16 @@
+#include <gtest/gtest.h>
+#include <vanetza/dcc/mapping.hpp>
+
+using namespace vanetza;
+using namespace vanetza::dcc;
+
+TEST(Mapping, map_profile_onto_ac)
+{
+    EXPECT_EQ(access::AccessCategory::VO, map_profile_onto_ac(Profile::DP0));
+    EXPECT_EQ(access::AccessCategory::VI, map_profile_onto_ac(Profile::DP1));
+    EXPECT_EQ(access::AccessCategory::BE, map_profile_onto_ac(Profile::DP2));
+    EXPECT_EQ(access::AccessCategory::BK, map_profile_onto_ac(Profile::DP3));
+
+    auto malicious_profile = static_cast<Profile>(4);
+    EXPECT_THROW(map_profile_onto_ac(malicious_profile), std::invalid_argument);
+}