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FLASHING.md says how to take a newer version of the colleague's tree (copy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

@@ -0,0 +1,61 @@
+#pragma once
+#include <vanetza/geodesy/country_polygon.hpp>
+#include <vanetza/geodesy/m49_code.hpp>
+#include <vanetza/geodesy/position.hpp>
+#include <cstddef>
+#include <string>
+#include <unordered_map>
+
+namespace vanetza
+{
+namespace geodesy
+{
+
+class CountryDatabase
+{
+public:
+    /**
+     * Create a CountryDatabase from embedded country data.
+     * Only available when built with VANETZA_WITH_EMBEDDED_COUNTRY_DATA.
+     * \param[out] error optional error message
+     * \return loaded database, or empty database on failure
+     */
+    static CountryDatabase embedded(std::string* error = nullptr);
+
+    /**
+     * Load country data from a file.
+     * \param[in] path path to the binary country data file
+     * \param[out] error optional error message
+     * \return true on success
+     */
+    bool load(const std::string& path, std::string* error = nullptr);
+
+    /**
+     * Load country data from a memory buffer.
+     * \param[in] data pointer to binary data
+     * \param[in] length size of data in bytes
+     * \param[out] error optional error message
+     * \return true on success
+     */
+    bool load(const uint8_t* data, std::size_t length, std::string* error = nullptr);
+
+    /**
+     * Check if a geodetic position lies within a country.
+     * \param country M.49 country code
+     * \param position geodetic position to check
+     * \return true if position is inside the country's boundaries
+     */
+    bool is_inside(M49Code country, const GeodeticPosition& position) const;
+
+    /**
+     * Check if the database contains any country data.
+     * \return true if no countries are loaded
+     */
+    bool empty() const;
+
+private:
+    std::unordered_map<M49Code, CountryPolygon> m_countries;
+};
+
+} // namespace geodesy
+} // namespace vanetza