Keep vanetza-idf in obu-firmware, so a plain clone builds the firmware

obu-firmware builds against the vanetza-idf C-ITS library, which until now
came from the colleague's microbu-esp32c5 tree beside the repository and was
not tracked here, so a clone of this repository could not build the firmware
it ships. The library alone is now part of obu-firmware, as
obu-firmware/external/vanetza-idf: their external/vanetza-idf at commit
cf4b99f, unchanged (9775 files; see its PROVENANCE.md). CMake takes it from
there by default; -DVANETZA_IDF_DIR still points the build elsewhere.

The rest of the colleague's tree (their own VAM firmware, PKI tooling,
station-link Python tools, the V2X2MAP bridge) stays out of this repository
and gitignored; nothing is pushed to their repository. NOTES.md, docs/06,
TODO.md and the pcap verifier's usage line point at the new location.

obu-firmware/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