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/asn1/COPYRIGHT.md

@@ -0,0 +1,47 @@
+These ASN.1 files are taken from their respective standardisation documents and are **not** licensed the same way as Vanetza itself.
+Please refer to the referenced standardisation documents for details about the applicable Intellectual Property Rights (IPR).
+To the best of my knowledge, ETSI does not object to bundling ASN.1 files of their published documents along with software.
+Some editorial changes may have been applied, e.g. removal of trailing whitespace etc.
+Code generated from the files located here can be found in the *vanetza/asn1/its* directory.
+
+# Standardisation documents
+
+- *EN302637-2v141-CAM.asn* from ETSI EN 302 637-2 v1.4.1 (2019-04)
+- *EN302637-3v131-DENM.asn* from  ETSI EN 302 637-3 v1.3.1 (2019-04)
+- *TS102894-2v131-CDD.asn* from ETSI TS 102 894-2 v1.3.1 (2018-08)
+- *TS102941v131-\*.asn* from ETSI TS 102 941 v1.3.1 (2019-02)
+- *TS103097v131.asn* from ETSI TS 103 097 v1.3.1 (2017-10)
+- *TS103097v211-\*.asn* from ETSI TS 103 097 v2.1.1 (2021-10)
+- *TR103562v211.asn* from ETSI TR 103 562 v2.1.1 (2019-12)
+
+- *IEEE1609dot2.asn* and *IEEE1609dot2BaseTypes.asn* from IEEE 1609.2 as printed in ETSI TS 103 097 v1.3.1
+
+# ETSI WebSVN
+
+You may find these ITS ASN.1 modules also in ETSI's public SVN repository: http://oldforge.etsi.org/websvn/listing.php?repname=ITS.ITS_ASN1
+While above source is still online (in March 2020), ETSI seems to have moved to https://forge.etsi.org/rep/ITS/ITS_ASN1 by now.
+This newer source also contains a license file explicitly. A copy is included below for reference.
+
+> Copyright 2019 ETSI
+>
+> Redistribution and use in source and binary forms, with or without
+> modification, are permitted provided that the following conditions are met:
+> 1. Redistributions of source code must retain the above copyright notice,
+>    this list of conditions and the following disclaimer.
+> 2. Redistributions in binary form must reproduce the above copyright notice,
+>    this list of conditions and the following disclaimer in the documentation
+>    and/or other materials provided with the distribution.
+> 3. Neither the name of the copyright holder nor the names of its contributors
+>    may be used to endorse or promote products derived from this software without
+>    specific prior written permission.
+>
+> THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+> ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+> WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+> IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
+> INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+> BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+> DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+> LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
+> OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+> OF THE POSSIBILITY OF SUCH DAMAGE.