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FLASHING.md says how to take a newer version of the colleague's tree (copy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

@@ -0,0 +1,52 @@
+#pragma once
+#include <boost/optional/optional_io.hpp>
+#include <vanetza/security/decap_service.hpp>
+#include <vanetza/security/hashed_id.hpp>
+#include <ostream>
+
+namespace vanetza
+{
+namespace security
+{
+
+void PrintTo(const DecapReport& report, std::ostream* out)
+{
+    struct Printer : boost::static_visitor<>
+    {
+        Printer(std::ostream* out) : out(out) {}
+
+        void operator()(const VerificationReport& report) const
+        {
+            *out << "DecapReport(VerificationReport(" << static_cast<int>(report) << "))";
+        }
+
+        void operator()(const boost::blank&) const
+        {
+            *out << "DecapReport(None)";
+        }
+
+        std::ostream* out;
+    };
+    boost::apply_visitor(Printer(out), report);
+}
+
+} // namespace security
+} // namespace vanetza
+
+namespace std {
+
+/* HashedId3 and HashedId8 are mere type aliases of std::array<> */
+
+std::ostream& operator<<(std::ostream& os, const vanetza::security::HashedId3& id)
+{
+    os << vanetza::security::to_string(id);
+    return os;
+}
+
+std::ostream& operator<<(std::ostream& os, const vanetza::security::HashedId8& id)
+{
+    os << vanetza::security::to_string(id);
+    return os;
+}
+
+} // namespace std