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/FindGeographicLib.cmake

@@ -0,0 +1,54 @@
+option(GeographicLib_PREFER_PACKAGE_CONFIG "Prefer CMake config mode" ON)
+mark_as_advanced(GeographicLib_PREFER_PACKAGE_CONFIG)
+
+if(GeographicLib_PREFER_PACKAGE_CONFIG)
+    find_package(GeographicLib ${GeographicLib_FIND_VERSION} QUIET CONFIG)
+    if (GeographicLib_FOUND)
+        message(STATUS "GeographicLib: using found CMake configuration")
+        return()
+    endif()
+endif()
+message(STATUS "GeographicLib: using lookup code by Vanetza")
+
+find_path(GeographicLib_INCLUDE_DIR NAMES GeographicLib/Config.h DOC "GeographicLib include directory")
+find_library(GeographicLib_LIBRARY_RELEASE NAMES Geographic GeographicLib DOC "GeographicLib library (release)")
+find_library(GeographicLib_LIBRARY_DEBUG NAMES Geographic_d GeographicLib_d DOC "GeographicLib library (debug)")
+
+include(SelectLibraryConfigurations)
+select_library_configurations(GeographicLib)
+
+if(GeographicLib_INCLUDE_DIR)
+    file(STRINGS ${GeographicLib_INCLUDE_DIR}/GeographicLib/Config.h _config_version REGEX "GEOGRAPHICLIB_VERSION_STRING")
+    string(REGEX MATCH "\"([0-9.]+)\"$" _match_version ${_config_version})
+    set(GeographicLib_VERSION_STRING ${CMAKE_MATCH_1})
+endif()
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(GeographicLib
+    REQUIRED_VARS GeographicLib_INCLUDE_DIR GeographicLib_LIBRARY
+    FOUND_VAR GeographicLib_FOUND
+    VERSION_VAR GeographicLib_VERSION_STRING)
+
+if(GeographicLib_FOUND AND NOT TARGET GeographicLib::GeographicLib)
+    add_library(GeographicLib::GeographicLib UNKNOWN IMPORTED)
+    set_target_properties(GeographicLib::GeographicLib PROPERTIES
+        INTERFACE_INCLUDE_DIRECTORIES "${GeographicLib_INCLUDE_DIR}"
+        IMPORTED_LOCATION "${GeographicLib_LIBRARY}"
+        IMPORTED_LINK_INTERFACE_LANGUAGES "CXX")
+    if(EXISTS "${GeographicLib_LIBRARY_RELEASE}")
+        set_property(TARGET GeographicLib::GeographicLib APPEND PROPERTY
+            IMPORTED_CONFIGURATIONS RELEASE)
+        set_target_properties(GeographicLib::GeographicLib PROPERTIES
+            IMPORTED_LOCATION_RELEASE "${GeographicLib_LIBRARY_RELEASE}")
+    endif()
+    if(EXISTS "${GeographicLib_LIBRARY_DEBUG}")
+        set_property(TARGET GeographicLib::GeographicLib APPEND PROPERTY
+            IMPORTED_CONFIGURATIONS DEBUG)
+        set_target_properties(GeographicLib::GeographicLib PROPERTIES
+            IMPORTED_LOCATION_DEBUG "${GeographicLib_LIBRARY_DEBUG}")
+    endif()
+endif()
+
+mark_as_advanced(GeographicLib_INCLUDE_DIR GeographicLib_LIBRARY)
+set(GeographicLib_INCLUDE_DIRS ${GeographicLib_INCLUDE_DIR})
+# GeographicLib_LIBRARIES is set by SelectLibraryConfigurations