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/geonet/tests/fake_interfaces.hpp

@@ -0,0 +1,46 @@
+#ifndef FAKE_INTERFACES_HPP
+#define FAKE_INTERFACES_HPP
+
+#include <vanetza/dcc/data_request.hpp>
+#include <vanetza/dcc/interface.hpp>
+#include <vanetza/geonet/transport_interface.hpp>
+#include <vanetza/geonet/data_indication.hpp>
+#include <vanetza/geonet/data_confirm.hpp>
+
+using namespace vanetza;
+
+class FakeRequestInterface : public dcc::RequestInterface
+{
+public:
+    FakeRequestInterface() : m_requests(0) {}
+
+    void request(const dcc::DataRequest& req, std::unique_ptr<ChunkPacket> packet) override
+    {
+        ++m_requests;
+        m_last_request = req;
+        m_last_packet = std::move(packet);
+    }
+
+    unsigned m_requests;
+    dcc::DataRequest m_last_request;
+    std::unique_ptr<ChunkPacket> m_last_packet;
+};
+
+class FakeTransportInterface : public geonet::TransportInterface
+{
+public:
+    FakeTransportInterface() : m_indications(0) {}
+
+    void indicate(const geonet::DataIndication& ind, std::unique_ptr<geonet::UpPacket> packet) override
+    {
+        ++m_indications;
+        m_last_indication = ind;
+        m_last_packet = std::move(packet);
+    }
+
+    unsigned m_indications;
+    boost::optional<geonet::DataIndication> m_last_indication;
+    std::unique_ptr<geonet::UpPacket> m_last_packet;
+};
+
+#endif // FAKE_INTERFACES_HPP