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FLASHING.md says how to take a newer version of the colleague's tree (copy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