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FLASHING.md says how to take a newer version of the colleague's tree (copy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/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@")