Keep vanetza-idf in obu-firmware, so a plain clone builds the firmware

obu-firmware builds against the vanetza-idf C-ITS library, which until now
came from the colleague's microbu-esp32c5 tree beside the repository and was
not tracked here, so a clone of this repository could not build the firmware
it ships. The library alone is now part of obu-firmware, as
obu-firmware/external/vanetza-idf: their external/vanetza-idf at commit
cf4b99f, unchanged (9775 files; see its PROVENANCE.md). CMake takes it from
there by default; -DVANETZA_IDF_DIR still points the build elsewhere.

The rest of the colleague's tree (their own VAM firmware, PKI tooling,
station-link Python tools, the V2X2MAP bridge) stays out of this repository
and gitignored; nothing is pushed to their repository. NOTES.md, docs/06,
TODO.md and the pcap verifier's usage line point at the new location.

obu-firmware/external/vanetza-idf/vanetza/common/serialization.hpp

@@ -0,0 +1,83 @@
+#ifndef SERIALIZATION_HPP_U2YGHSPB
+#define SERIALIZATION_HPP_U2YGHSPB
+
+#include <vanetza/common/archives.hpp>
+#include <vanetza/common/byte_order.hpp>
+#include <boost/units/quantity.hpp>
+#include <type_traits>
+
+namespace vanetza
+{
+
+template<typename T, ByteOrder ORDER>
+void serialize(OutputArchive& ar, EndianType<T, ORDER> value)
+{
+    typedef typename decltype(value)::network_type network_type;
+    T tmp = static_cast<network_type>(value).get();
+    ar << tmp;
+}
+
+template<typename T, ByteOrder ORDER>
+void deserialize(InputArchive& ar, EndianType<T, ORDER>& value)
+{
+    T tmp;
+    ar >> tmp;
+    value = network_cast<T>(tmp);
+}
+
+template<typename T>
+typename std::enable_if<std::is_integral<T>::value>::type
+serialize(OutputArchive& ar, T value)
+{
+    auto tmp = hton(value);
+    ar << tmp;
+}
+
+template<typename T>
+typename std::enable_if<std::is_integral<T>::value>::type
+deserialize(InputArchive& ar, T& value)
+{
+    T tmp;
+    ar >> tmp;
+    value = ntoh(tmp);
+}
+
+template<typename U, typename T>
+void serialize(OutputArchive& ar, boost::units::quantity<U, T> q)
+{
+    static_assert(std::is_integral<T>::value,
+            "Only integral based quantities are supported");
+    auto tmp = hton(q.value());
+    ar << tmp;
+}
+
+template<typename U, typename T>
+void deserialize(InputArchive& ar, boost::units::quantity<U, T>& q)
+{
+    static_assert(std::is_integral<T>::value,
+            "Only integral based quantities are supported");
+    T tmp;
+    ar >> tmp;
+    q = boost::units::quantity<U, T>::from_value(ntoh(tmp));
+}
+
+template<class T>
+typename std::enable_if<std::is_enum<T>::value>::type
+serialize(OutputArchive& ar, const T& t)
+{
+    serialize(ar, host_cast(static_cast<typename std::underlying_type<T>::type const>(t)));
+}
+
+template<class T>
+typename std::enable_if<std::is_enum<T>::value>::type
+deserialize(InputArchive& ar, T& t)
+{
+    typename std::underlying_type<T>::type tmp;
+    deserialize(ar, tmp);
+    t = static_cast<T>(tmp);
+}
+
+} // namespace vanetza
+
+#endif /* SERIALIZATION_HPP_U2YGHSPB */
+