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FLASHING.md says how to take a newer version of the colleague's tree (copy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

@@ -0,0 +1,36 @@
+#include "mapping.hpp"
+#include <stdexcept>
+
+namespace vanetza
+{
+namespace dcc
+{
+
+access::AccessCategory map_profile_onto_ac(Profile dp_id)
+{
+    access::AccessCategory ac = access::AccessCategory::BE;
+
+    switch (dp_id)
+    {
+        case Profile::DP0:
+            ac = access::AccessCategory::VO;
+            break;
+        case Profile::DP1:
+            ac = access::AccessCategory::VI;
+            break;
+        case Profile::DP2:
+            ac = access::AccessCategory::BE;
+            break;
+        case Profile::DP3:
+            ac = access::AccessCategory::BK;
+            break;
+        default:
+            throw std::invalid_argument("Invalid DCC Profile ID");
+            break;
+    }
+
+    return ac;
+}
+
+} // namespace dcc
+} // namespace vanetza