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FLASHING.md says how to take a newer version of the colleague's tree (copy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/geonet/traffic_class.hpp

@@ -0,0 +1,46 @@
+#ifndef TRAFFIC_CLASS_HPP_I2WYKREX
+#define TRAFFIC_CLASS_HPP_I2WYKREX
+
+#include <vanetza/common/bit_number.hpp>
+#include <vanetza/dcc/profile.hpp>
+#include <vanetza/geonet/serialization.hpp>
+#include <cstdint>
+
+namespace vanetza
+{
+
+namespace geonet
+{
+
+class TrafficClass
+{
+public:
+    TrafficClass();
+    TrafficClass(bool scf, bool channel_offload, BitNumber<unsigned, 6> tc_id);
+    explicit TrafficClass(uint8_t raw);
+
+    bool store_carry_forward() const;
+    void store_carry_forward(bool flag);
+    bool channel_offload() const;
+    void channel_offload(bool flag);
+    BitNumber<unsigned, 6> tc_id() const;
+    void tc_id(BitNumber<unsigned, 6> id);
+    uint8_t raw() const { return m_tc; }
+
+private:
+    static constexpr uint8_t scf_mask = 0x80;
+    static constexpr uint8_t channel_offload_mask = 0x40;
+    static constexpr uint8_t tc_id_mask = 0x3f;
+    uint8_t m_tc;
+};
+
+dcc::Profile map_tc_onto_profile(const TrafficClass&);
+
+void serialize(const TrafficClass&, OutputArchive&);
+void deserialize(TrafficClass&, InputArchive&);
+
+} // namespace geonet
+} // namespace vanetza
+
+#endif /* TRAFFIC_CLASS_HPP_I2WYKREX */
+