Keep vanetza-idf in obu-firmware, so a plain clone builds the firmware

obu-firmware builds against the vanetza-idf C-ITS library, which until now
came from the colleague's microbu-esp32c5 tree beside the repository and was
not tracked here, so a clone of this repository could not build the firmware
it ships. The library alone is now part of obu-firmware, as
obu-firmware/external/vanetza-idf: their external/vanetza-idf at commit
cf4b99f, unchanged (9775 files; see its PROVENANCE.md). CMake takes it from
there by default; -DVANETZA_IDF_DIR still points the build elsewhere.

The rest of the colleague's tree (their own VAM firmware, PKI tooling,
station-link Python tools, the V2X2MAP bridge) stays out of this repository
and gitignored; nothing is pushed to their repository. NOTES.md, docs/06,
TODO.md and the pcap verifier's usage line point at the new location.

obu-firmware/external/vanetza-idf/tools/socktap/positioning.cpp

@@ -0,0 +1,55 @@
+#include "positioning.hpp"
+#include <vanetza/common/stored_position_provider.hpp>
+
+#ifdef SOCKTAP_WITH_GPSD
+#   include "gps_position_provider.hpp"
+#endif
+
+using namespace vanetza;
+namespace po = boost::program_options;
+
+std::unique_ptr<vanetza::PositionProvider>
+create_position_provider(boost::asio::io_context& io_context, const po::variables_map& vm, const Runtime& runtime)
+{
+    std::unique_ptr<vanetza::PositionProvider> positioning;
+
+    if (vm["positioning"].as<std::string>() == "gpsd") {
+#ifdef SOCKTAP_WITH_GPSD
+        positioning.reset(new GpsPositionProvider {
+            io_context, vm["gpsd-host"].as<std::string>(), vm["gpsd-port"].as<std::string>()
+        });
+#endif
+    } else if (vm["positioning"].as<std::string>() == "static") {
+        std::unique_ptr<StoredPositionProvider> stored { new StoredPositionProvider() };
+        PositionFix fix;
+        fix.timestamp = runtime.now();
+        fix.latitude = vm["latitude"].as<double>() * units::degree;
+        fix.longitude = vm["longitude"].as<double>() * units::degree;
+        fix.confidence.semi_major = vm["pos_confidence"].as<double>() * units::si::meter;
+        fix.confidence.semi_minor = fix.confidence.semi_major;
+        stored->position_fix(fix);
+        positioning = std::move(stored);
+    }
+
+    return positioning;
+}
+
+void add_positioning_options(po::options_description& options)
+{
+#ifdef SOCKTAP_WITH_GPSD
+    const char* default_positioning = "gpsd";
+#else
+    const char* default_positioning = "static";
+#endif
+
+    options.add_options()
+        ("positioning,p", po::value<std::string>()->default_value(default_positioning), "Select positioning provider")
+#ifdef SOCKTAP_WITH_GPSD
+        ("gpsd-host", po::value<std::string>()->default_value("localhost"), "gpsd's server hostname")
+        ("gpsd-port", po::value<std::string>()->default_value(gpsd::default_port), "gpsd's listening port")
+#endif
+        ("latitude", po::value<double>()->default_value(48.7668616), "Latitude of static position")
+        ("longitude", po::value<double>()->default_value(11.432068), "Longitude of static position")
+        ("pos_confidence", po::value<double>()->default_value(5.0), "95% circular confidence of static position")
+    ;
+}