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FLASHING.md says how to take a newer version of the colleague's tree (copy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/fuzz-harness/persistent.cpp

@@ -0,0 +1,34 @@
+#include "router_fuzzing_context.hpp"
+#include <stdio.h>
+#include <unistd.h>
+
+#ifndef __AFL_FUZZ_TESTCASE_LEN
+ssize_t fuzz_len;
+#define __AFL_FUZZ_TESTCASE_LEN fuzz_len
+unsigned char fuzz_buf[1024000];
+#define __AFL_FUZZ_TESTCASE_BUF fuzz_buf
+#define __AFL_FUZZ_INIT() void sync(void);
+#define __AFL_LOOP(x) ((fuzz_len = read(0, fuzz_buf, sizeof(fuzz_buf))) > 0 ? 1 : 0)
+#define __AFL_INIT() sync()
+#endif
+
+__AFL_FUZZ_INIT();
+
+int main()
+{
+#ifdef __AFL_HAVE_MANUAL_CONTROL
+    __AFL_INIT();
+#endif
+
+    vanetza::RouterFuzzingContext context;
+
+    unsigned char *buf = __AFL_FUZZ_TESTCASE_BUF;
+    while (__AFL_LOOP(10000)) {
+        int len = __AFL_FUZZ_TESTCASE_LEN;
+        vanetza::ByteBuffer buffer { buf, buf + len };
+        context.initialize();
+        context.indicate(std::move(buffer));
+    }
+
+    return 0;
+}