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FLASHING.md says how to take a newer version of the colleague's tree (copy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

@@ -0,0 +1,36 @@
+#pragma once
+
+#include <vanetza/units/angle.hpp>
+#include <vanetza/units/length.hpp>
+
+namespace vanetza
+{
+namespace geodesy
+{
+
+/**
+ * Cartesian position.
+ * Point in an ENU (East-North-Up) coordinate system, units in meters.
+ */
+struct CartesianPosition
+{
+    CartesianPosition() : x(0.0 * units::si::meter), y(0.0 * units::si::meter) {}
+    CartesianPosition(units::Length x_, units::Length y_) : x(x_), y(y_) {}
+    units::Length x;
+    units::Length y;
+};
+
+CartesianPosition operator-(const CartesianPosition&, const CartesianPosition&);
+
+struct GeodeticPosition
+{
+    GeodeticPosition() :
+        latitude(0.0 * units::degree), longitude(0.0 * units::degree) {}
+    GeodeticPosition(units::GeoAngle lat, units::GeoAngle lon) :
+        latitude(lat), longitude(lon) {}
+    units::GeoAngle latitude;
+    units::GeoAngle longitude;
+};
+
+} // namespace geodesy
+} // namespace vanetza