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/repeater.hpp

@@ -0,0 +1,77 @@
+#ifndef REPEATER_HPP_AH49FXB1
+#define REPEATER_HPP_AH49FXB1
+
+#include <vanetza/common/clock.hpp>
+#include <vanetza/geonet/data_request.hpp>
+#include <vanetza/geonet/packet.hpp>
+#include <functional>
+#include <list>
+#include <memory>
+
+namespace vanetza
+{
+// forward declaration
+class Runtime;
+
+namespace geonet
+{
+
+/**
+ * Repeater eases handling of packet repetitions.
+ * Packet repetitions are repeated requests with same payload.
+ */
+class Repeater
+{
+public:
+    using Callback = std::function<void(const DataRequestVariant&, std::unique_ptr<DownPacket>)>;
+
+    /**
+     * Create a Repeater instance
+     * \param rt runtime used for scheduling repetitions
+     * \param cb callback to be invoked when repetition is due
+     */
+    Repeater(Runtime& rt, const Callback& cb);
+    ~Repeater();
+
+    /**
+     * Add another repetition
+     * \param request any kind of GeoNet data request
+     * \param payload request's payload
+     */
+    template<class REQUEST>
+    void add(const REQUEST& request, const DownPacket& payload)
+    {
+        if (request.repetition) {
+            add(request, *request.repetition, payload);
+        }
+    }
+
+private:
+    struct Repetition
+    {
+        Repetition(const DataRequestVariant&, const DownPacket&);
+
+        DataRequestVariant m_request;
+        std::unique_ptr<DownPacket> m_payload;
+    };
+
+    /**
+     * Add packet repetition to internal book keeping
+     */
+    void add(const DataRequestVariant&, const DataRequest::Repetition&, const DownPacket&);
+
+    /**
+     * Triggered when repetition is due according to runtime
+     */
+    void trigger(std::list<Repetition>::iterator, Clock::time_point);
+
+    std::list<Repetition> m_repetitions;
+    Callback m_repeat_fn;
+    Runtime& m_runtime;
+};
+
+} // namespace geonet
+} // namespace vanetza
+
+#endif /* REPEATER_HPP_AH49FXB1 */
+