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/vanetza/asn1/support/aper_decoder.h

@@ -0,0 +1,47 @@
+/*-
+ * Copyright (c) 2005-2017 Lev Walkin <vlm@lionet.info>. All rights reserved.
+ * Redistribution and modifications are permitted subject to BSD license.
+ */
+#ifndef	_APER_DECODER_H_
+#define	_APER_DECODER_H_
+
+#include "asn_application.h"
+#include "aper_support.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct asn_TYPE_descriptor_s;	/* Forward declaration */
+
+/*
+ * Aligned PER decoder of a "complete encoding" as per X.691#10.1.
+ * On success, this call always returns (.consumed >= 1), in BITS, as per X.691#10.1.3.
+ */
+asn_dec_rval_t aper_decode_complete(
+       const struct asn_codec_ctx_s *opt_codec_ctx,
+       const struct asn_TYPE_descriptor_s *type_descriptor,	/* Type to decode */
+       void **struct_ptr,	/* Pointer to a target structure's pointer */
+       const void *buffer,	/* Data to be decoded */
+       size_t size		/* Size of data buffer */
+									);
+
+/*
+ * Aligned PER decoder of any ASN.1 type. May be invoked by the application.
+ * WARNING: This call returns the number of BITS read from the stream. Beware.
+ */
+asn_dec_rval_t aper_decode(
+      const struct asn_codec_ctx_s *opt_codec_ctx,
+      const struct asn_TYPE_descriptor_s *type_descriptor,	/* Type to decode */
+      void **struct_ptr,	/* Pointer to a target structure's pointer */
+      const void *buffer,	/* Data to be decoded */
+      size_t size,		/* Size of data buffer */
+      int skip_bits,		/* Number of unused leading bits, 0..7 */
+      int unused_bits		/* Number of unused tailing bits, 0..7 */
+      );
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif	/* _APER_DECODER_H_ */