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FLASHING.md says how to take a newer version of the colleague's tree (copy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/tools/docker/apt_pkg_name.sh

@@ -0,0 +1,26 @@
+#!/bin/bash
+set -euo pipefail
+
+source /etc/os-release
+case $VERSION_CODENAME in
+  bionic|focal|jammy)
+    GEOGRAPHICLIB=libgeographic-dev
+    ;;
+  noble|resolute)
+    GEOGRAPHICLIB=libgeographiclib-dev
+    ;;
+  *)
+    echo "Unsupported Ubuntu version: $VERSION_CODENAME"
+    exit 1
+    ;;
+esac
+
+case $1 in
+  geographiclib)
+    echo $GEOGRAPHICLIB
+    ;;
+  *)
+    echo "Unknown package name: $1"
+    exit 1
+    ;;
+esac