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/facilities/detail/macros.ipp

@@ -0,0 +1,29 @@
+#pragma once
+
+#define ASN1_RELEASE2_PREFIX Vanetza_ITS2_
+#define ASN1_RELEASE1_PREFIX
+
+#define ASN1_CONCAT(x, y) ASN1_CONCAT_AGAIN(x, y)
+#define ASN1_CONCAT_AGAIN(x, y) x ## y
+
+#define ASN1_RELEASE1_NAME(name) ASN1_CONCAT(ASN1_RELEASE1_PREFIX, name)
+#define ASN1_RELEASE2_NAME(name) ASN1_CONCAT(ASN1_RELEASE2_PREFIX, name)
+
+/**
+ * Prepend code generation prefix to an ASN.1 name or type.
+ */
+#define ASN1_PREFIXED(name) ASN1_CONCAT(ASN1_PREFIX, name)
+
+/**
+ * Check that enum name has equal value in both releases. 
+ */
+#define ASSERT_EQUAL_ENUM(name) \
+    static_assert(int(ASN1_RELEASE1_NAME(name)) == int(ASN1_RELEASE2_NAME(name)), \
+    #name " mismatch between release 1 and 2");
+
+/**
+ * Check that types are equal in both releases
+ */
+#define ASSERT_EQUAL_TYPE(name) \
+    static_assert(std::is_same<ASN1_RELEASE1_NAME(name), ASN1_RELEASE2_NAME(name)>::value, \
+    #name " type mismatch between release 1 and 2");