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FLASHING.md says how to take a newer version of the colleague's tree (copy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

@@ -0,0 +1,60 @@
+#include "repeater.hpp"
+#include "data_request.hpp"
+#include <vanetza/common/runtime.hpp>
+#include <cassert>
+
+namespace vanetza
+{
+namespace geonet
+{
+
+Repeater::Repetition::Repetition(const DataRequestVariant& request, const DownPacket& payload) :
+    m_request(request), m_payload(new DownPacket(payload))
+{
+}
+
+Repeater::Repeater(Runtime& rt, const Callback& cb) :  m_repeat_fn(cb), m_runtime(rt)
+{
+    assert(m_repeat_fn);
+}
+
+Repeater::~Repeater()
+{
+    m_runtime.cancel(this);
+}
+
+void Repeater::add(const DataRequestVariant& request,
+        const DataRequest::Repetition& repetition, const DownPacket& payload)
+{
+    if (has_further_repetition(repetition)) {
+        const auto next_repetition = m_runtime.now() + units::clock_cast(repetition.interval);
+        m_repetitions.emplace_front(request, payload);
+        auto added = m_repetitions.begin();
+        auto then = std::placeholders::_1;
+        m_runtime.schedule(next_repetition, std::bind<void>(&Repeater::trigger, this, added, then), this);
+    }
+}
+
+void Repeater::trigger(std::list<Repetition>::iterator rep, Clock::time_point invocation)
+{
+    Repetition& repetition = *rep;
+    DataRequest& request = access_request(repetition.m_request);
+    assert(request.repetition);
+
+    // reduce remaining interval by one step and occurred triggering delay
+    decrement_by_one(*request.repetition);
+    auto delayed = m_runtime.now() - invocation;
+    request.repetition->maximum -= units::clock_cast(delayed);
+
+    // reset repetition data if this is the last repetition
+    if (!has_further_repetition(request)) {
+        request.repetition.reset();
+    }
+
+    m_repeat_fn(repetition.m_request, std::move(repetition.m_payload));
+    m_repetitions.erase(rep);
+}
+
+} // namespace geonet
+} // namespace vanetza
+