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FLASHING.md says how to take a newer version of the colleague's tree (copy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/vanetza/asn1/its/SegmentCount.h

@@ -0,0 +1,48 @@
+/*
+ * Generated by asn1c
+ * From ASN.1 module "CPM-PDU-Descriptions"
+ * 	found in "TR103562v211-CPM.asn"
+ * 	`asn1c -fcompound-names -fincludes-quoted -no-gen-example -R`
+ */
+
+#ifndef	_SegmentCount_H_
+#define	_SegmentCount_H_
+
+
+#include "asn_application.h"
+
+/* Including external dependencies */
+#include "NativeInteger.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* SegmentCount */
+typedef long	 SegmentCount_t;
+
+/* Implementation */
+extern asn_oer_constraints_t asn_OER_type_SegmentCount_constr_1;
+extern asn_per_constraints_t asn_PER_type_SegmentCount_constr_1;
+extern asn_TYPE_descriptor_t asn_DEF_SegmentCount;
+asn_struct_free_f SegmentCount_free;
+asn_struct_print_f SegmentCount_print;
+asn_constr_check_f SegmentCount_constraint;
+ber_type_decoder_f SegmentCount_decode_ber;
+der_type_encoder_f SegmentCount_encode_der;
+xer_type_decoder_f SegmentCount_decode_xer;
+xer_type_encoder_f SegmentCount_encode_xer;
+jer_type_encoder_f SegmentCount_encode_jer;
+oer_type_decoder_f SegmentCount_decode_oer;
+oer_type_encoder_f SegmentCount_encode_oer;
+per_type_decoder_f SegmentCount_decode_uper;
+per_type_encoder_f SegmentCount_encode_uper;
+per_type_decoder_f SegmentCount_decode_aper;
+per_type_encoder_f SegmentCount_encode_aper;
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif	/* _SegmentCount_H_ */
+#include "asn_internal.h"