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/facilities/detail/path_history.ipp

@@ -0,0 +1,38 @@
+#include <vanetza/asn1/asn1c_wrapper.hpp>
+#include <vanetza/asn1/its/BasicVehicleContainerLowFrequency.h>
+#include <vanetza/asn1/its/PathHistory.h>
+#include <vanetza/asn1/its/r2/BasicVehicleContainerLowFrequency.h>
+#include <vanetza/asn1/its/r2/Path.h>
+#include <vanetza/asn1/its/r2/PathHistory.h>
+#include <vanetza/facilities/detail/macros.ipp>
+#include <vanetza/facilities/detail/path_history.tpp>
+
+namespace vanetza
+{
+namespace facilities
+{
+
+static_assert(DeltaLongitude_oneMicrodegreeEast == 10, "DeltaLongitude is an integer number of tenth microdegrees");
+static_assert(DeltaLatitude_oneMicrodegreeNorth == 10, "DeltaLatitude is an integer number of tenth microdegrees");
+static_assert(PathDeltaTime_tenMilliSecondsInPast == 1, "PathDeltaTime encodes 10ms steps");
+
+void copy(const facilities::PathHistory& src, ASN1_PREFIXED(PathHistory_t)& dest)
+{
+    copy<ASN1_PREFIXED(PathHistory_t), ASN1_PREFIXED(PathPoint_t)>(src, dest);
+}
+
+#if ITS_RELEASE != 1
+// no Path_t in ITS Release 1 ASN.1
+void copy(const facilities::PathHistory& src, ASN1_PREFIXED(Path_t)& dest)
+{
+    copy<ASN1_PREFIXED(Path_t), ASN1_PREFIXED(PathPoint_t)>(src, dest);
+}
+#endif
+
+void copy(const facilities::PathHistory& ph, ASN1_PREFIXED(BasicVehicleContainerLowFrequency)& container)
+{
+    copy(ph, container.pathHistory);
+}
+
+} // namespace facilities
+} // namespace vanetza