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FLASHING.md says how to take a newer version of the colleague's tree (copy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

@@ -0,0 +1,47 @@
+#ifndef GPS_POSITION_PROVIDER_HPP_GYN3GVQA
+#define GPS_POSITION_PROVIDER_HPP_GYN3GVQA
+
+#include "positioning.hpp"
+#include <vanetza/common/clock.hpp>
+#include <vanetza/common/position_provider.hpp>
+#include <boost/asio/io_context.hpp>
+#include <boost/asio/steady_timer.hpp>
+#include <string>
+#include <gps.h>
+
+class GpsPositionProvider : public vanetza::PositionProvider
+{
+public:
+    class GpsPositioningException : public PositioningException
+    {
+    protected:
+        GpsPositioningException(int);
+        friend class GpsPositionProvider;
+    };
+
+    GpsPositionProvider(boost::asio::io_context& io);
+    GpsPositionProvider(boost::asio::io_context& io, const std::string& hostname, const std::string& port);
+    ~GpsPositionProvider();
+
+    const vanetza::PositionFix& position_fix() override;
+    void fetch_position_fix();
+
+private:
+    void schedule_timer();
+    void on_timer(const boost::system::error_code& ec);
+    bool apply_gps_data(const gps_data_t&);
+
+    boost::asio::steady_timer timer_;
+    gps_data_t gps_data_;
+    vanetza::PositionFix fetched_position_fix_;
+};
+
+namespace gpsd
+{
+
+constexpr const char* default_port = DEFAULT_GPSD_PORT;
+constexpr const char* shared_memory = GPSD_SHARED_MEMORY;
+
+} // namespace gpsd
+
+#endif /* GPS_POSITION_PROVIDER_HPP_GYN3GVQA */