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FLASHING.md says how to take a newer version of the colleague's tree (copy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

@@ -0,0 +1,32 @@
+#ifndef POSITION_CONFIDENCE_HPP_FNHKVJZL
+#define POSITION_CONFIDENCE_HPP_FNHKVJZL
+
+#include <vanetza/units/angle.hpp>
+#include <vanetza/units/length.hpp>
+#include <cmath>
+#include <limits>
+
+namespace vanetza
+{
+
+struct PositionConfidence
+{
+    PositionConfidence() :
+        semi_major(units::Length::from_value(std::numeric_limits<units::Length::value_type>::infinity())),
+        semi_minor(units::Length::from_value(std::numeric_limits<units::Length::value_type>::infinity()))
+    {}
+
+    operator bool() const
+    {
+        return !std::isinf(semi_major.value()) && semi_minor.value() <= semi_major.value() && semi_minor.value() >= 0.0;
+    }
+
+    units::Length semi_major;
+    units::Length semi_minor;
+    units::TrueNorth orientation;
+};
+
+} // namespace vanetza
+
+#endif /* POSITION_CONFIDENCE_HPP_FNHKVJZL */
+