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FLASHING.md says how to take a newer version of the colleague's tree (copy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

@@ -0,0 +1,29 @@
+#ifndef DATA_REQUEST_HPP_A5DWTTJN
+#define DATA_REQUEST_HPP_A5DWTTJN
+
+#include <vanetza/common/byte_order.hpp>
+#include <vanetza/common/clock.hpp>
+#include <vanetza/dcc/profile.hpp>
+#include <vanetza/net/mac_address.hpp>
+
+namespace vanetza
+{
+namespace dcc
+{
+
+struct DataRequest
+{
+    DataRequest() : dcc_profile(Profile::DP0) {}
+
+    uint16be_t ether_type;
+    MacAddress source;
+    MacAddress destination;
+    Profile dcc_profile;
+    Clock::duration lifetime;
+};
+
+} // namespace dcc
+} // namespace vanetza
+
+#endif /* DATA_REQUEST_HPP_A5DWTTJN */
+