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FLASHING.md says how to take a newer version of the colleague's tree (copy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

@@ -0,0 +1,60 @@
+#ifndef GEONET_ADDRESS_HPP_MB8J1IVQ
+#define GEONET_ADDRESS_HPP_MB8J1IVQ
+
+#include <vanetza/common/bit_number.hpp>
+#include <vanetza/net/mac_address.hpp>
+#include <vanetza/geonet/serialization.hpp>
+#include <vanetza/geonet/station_type.hpp>
+#include <functional>
+#include <type_traits>
+
+namespace vanetza
+{
+namespace geonet
+{
+
+class Address
+{
+public:
+    static constexpr std::size_t length_bytes = 8;
+
+    Address();
+    explicit Address(const MacAddress&);
+    bool is_manually_configured() const { return m_manually_configured; }
+    void is_manually_configured(bool flag) { m_manually_configured = flag; }
+    StationType station_type() const { return m_station_type; }
+    void station_type(StationType type) { m_station_type = type; }
+    BitNumber<unsigned, 10> country_code() const { return m_country_code; }
+    void country_code(BitNumber<unsigned, 10> country) { m_country_code = country; }
+    const MacAddress& mid() const { return m_mid; }
+    void mid(const MacAddress& mid) { m_mid = mid; }
+
+    bool operator==(const Address& other) const;
+    bool operator!=(const Address& other) const;
+
+private:
+    bool m_manually_configured; // 1 bit
+    StationType m_station_type; // 5 bit
+    BitNumber<unsigned, 10> m_country_code; // 10 bit (deprecated since 1.3.1)
+    MacAddress m_mid; // 48 bit
+};
+
+void serialize(const Address&, OutputArchive&);
+void deserialize(Address&, InputArchive&);
+
+} // namespace geonet
+} // namespace vanetza
+
+
+namespace std {
+
+template<>
+struct hash<vanetza::geonet::Address>
+{
+    size_t operator()(const vanetza::geonet::Address& addr) const;
+};
+
+} // namespace std
+
+#endif /* GEONET_ADDRESS_HPP_MB8J1IVQ */
+