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FLASHING.md says how to take a newer version of the colleague's tree (copy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/dcc/fully_meshed_state_machine.hpp

@@ -0,0 +1,105 @@
+#ifndef FULLY_MESHED_STATE_MACHINE_HPP_YPE958OH
+#define FULLY_MESHED_STATE_MACHINE_HPP_YPE958OH
+
+#include <vanetza/common/clock.hpp>
+#include <vanetza/dcc/channel_load.hpp>
+#include <vanetza/dcc/state_machine.hpp>
+#include <boost/circular_buffer.hpp>
+#include <boost/optional.hpp>
+
+namespace vanetza
+{
+namespace dcc
+{
+
+// constants
+static constexpr Clock::duration NDL_minDccSampling = std::chrono::milliseconds(100);
+
+
+class State
+{
+public:
+    virtual Clock::duration transmission_interval() const = 0;
+    virtual const char* name() const = 0;
+    virtual ~State() {}
+};
+
+class Relaxed : public State
+{
+public:
+    Clock::duration transmission_interval() const override;
+    const char* name() const override;
+};
+
+class Active : public State
+{
+public:
+    Active();
+    void update(double min, double max);
+    Clock::duration transmission_interval() const override;
+    const char* name() const override;
+
+private:
+    static const std::size_t sc_substates;
+    std::size_t m_substate;
+};
+
+class Restrictive : public State
+{
+public:
+    Clock::duration transmission_interval() const override;
+    const char* name() const override;
+};
+
+/**
+ * Fully meshed TRC state machine as per TS 102 687 v1.1.1
+ *
+ * States are modelled according to C2C-CC DCC Whitepaper / BSP v1.2
+ * State transitions are deferred internally for ramping up and cooling down over time.
+ */
+class FullyMeshedStateMachine : public StateMachine
+{
+public:
+    FullyMeshedStateMachine();
+    ~FullyMeshedStateMachine();
+
+    /**
+     * Notify state machine about current channel load.
+     * This method expects to be called in regular intervals
+     * of NDL_minDccSampling length.
+     */
+    void update(ChannelLoad channel_load);
+
+    /**
+     * Get currently allowed maximum message rate depending on state
+     * \return messages per second
+     */
+    double message_rate() const;
+
+    /**
+     * Get advised transmission interval between consecutive messages
+     * \return message transmission interval
+     */
+    Clock::duration transmission_interval() const;
+
+    /**
+     * Get state machine's active state
+     */
+    const State& state() const;
+
+private:
+    double max_channel_load() const;
+    double min_channel_load() const;
+
+    Relaxed m_relaxed;
+    Active m_active;
+    Restrictive m_restrictive;
+    State* m_state;
+    boost::circular_buffer<ChannelLoad> m_channel_loads;
+};
+
+} // namespace dcc
+} // namespace vanetza
+
+#endif /* FULLY_MESHED_STATE_MACHINE_HPP_YPE958OH */
+