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/cmake/VanetzaConfig.cmake.in

@@ -0,0 +1,38 @@
+@PACKAGE_INIT@
+
+# Temporarily extend module path for bundled find package scripts
+set(_vanetza_save_cmake_module_path ${CMAKE_MODULE_PATH})
+list(APPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_LIST_DIR})
+
+include(CMakeFindDependencyMacro)
+find_dependency(Boost @Boost_VERSION_STRING@ CONFIG COMPONENTS date_time)
+
+if(@VANETZA_WITH_GEOGRAPHICLIB@)
+    find_dependency(GeographicLib @GeographicLib_VERSION_STRING@)
+endif()
+
+if(@VANETZA_WITH_RPC@)
+    find_dependency(CapnProto @CapnProto_VERSION@)
+endif()
+
+if(@VANETZA_WITH_CRYPTOPP@)
+    find_dependency(CryptoPP @CryptoPP_VERSION_STRING@)
+endif()
+
+if(@VANETZA_WITH_OPENSSL@)
+    # remove patch letter found with OpenSSL 1.x
+    string(REGEX REPLACE "[a-z]+$" "" OpenSSL_VERSION_WITHOUT_PATCH "@OpenSSL_VERSION@")
+    find_dependency(OpenSSL ${OpenSSL_VERSION_WITHOUT_PATCH})
+endif()
+
+if(@VANETZA_WITH_PQC@)
+    find_dependency(liboqs 0.14 CONFIG)
+endif()
+
+# Restore previous module path
+set(CMAKE_MODULE_PATH ${_vanetza_save_cmake_module_path})
+unset(_vanetza_save_cmake_module_path)
+
+include("${CMAKE_CURRENT_LIST_DIR}/VanetzaTargets.cmake")
+
+set_and_check(VANETZA_INCLUDE_DIR "@PACKAGE_CMAKE_INSTALL_INCLUDEDIR@")