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FLASHING.md says how to take a newer version of the colleague's tree (copy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

@@ -0,0 +1,54 @@
+#include <vanetza/common/runtime.hpp>
+#include <vanetza/geonet/dcc_information_sharing.hpp>
+#include <vanetza/geonet/location_table.hpp>
+
+namespace vanetza
+{
+namespace geonet
+{
+
+DccInformationSharing::DccInformationSharing(Runtime& rt, const LocationTable& lt, dcc::ChannelLoad target, UnitInterval delay) :
+    m_runtime(rt), m_location_table(lt), m_cbr_target(target), m_tx_power(0),
+    m_trigger_interval(std::chrono::milliseconds(100)),
+    m_last_aggregation(m_runtime.now()),
+    on_global_cbr_update(m_update_hook)
+{
+    Clock::duration initial = m_trigger_interval;
+    initial *= delay.value();
+    m_runtime.schedule(initial, [this](const Clock::time_point&) { trigger(); });
+}
+
+DccInformationSharing::DccInformationSharing(Runtime& rt, const LocationTable& lt, dcc::ChannelLoad target) :
+    DccInformationSharing(rt, lt, target, UnitInterval { 0.0 })
+{
+}
+
+DccField DccInformationSharing::generate_dcc_field()
+{
+    DccMcoField dcc_mco;
+    dcc_mco.local_cbr(m_aggregator.get_local_cbr());
+    dcc_mco.neighbour_cbr(m_aggregator.get_one_hop_cbr());
+    dcc_mco.output_power(m_tx_power);
+    return dcc_mco;
+}
+
+void DccInformationSharing::update_local_cbr(dcc::ChannelLoad local_cbr)
+{
+    m_cbr_local = local_cbr;
+}
+
+void DccInformationSharing::set_tx_power(unsigned tx_power)
+{
+    m_tx_power = tx_power;
+}
+
+void DccInformationSharing::trigger()
+{
+    m_aggregator.aggregate(m_cbr_local, m_location_table, m_last_aggregation, m_cbr_target);
+    m_last_aggregation = m_runtime.now();
+    m_update_hook(static_cast<const CbrAggregator&>(m_aggregator));
+    m_runtime.schedule(m_trigger_interval, [this](const Clock::time_point&) { trigger(); });
+}
+
+} // namespace geonet
+} // namespace vanetza