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FLASHING.md says how to take a newer version of the colleague's tree (copy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/geonet/parser.hpp

@@ -0,0 +1,45 @@
+#ifndef PARSER_HPP_IBDRMPKB
+#define PARSER_HPP_IBDRMPKB
+
+#include <vanetza/common/byte_buffer.hpp>
+#include <vanetza/common/byte_buffer_source.hpp>
+#include <vanetza/geonet/header_type.hpp>
+#include <vanetza/geonet/header_variant.hpp>
+#include <vanetza/security/secured_message.hpp>
+#include <boost/iostreams/stream.hpp>
+#include <boost/range/iterator_range.hpp>
+#include <cstdint>
+
+namespace vanetza
+{
+namespace geonet
+{
+
+// forward declarations
+struct BasicHeader;
+struct CommonHeader;
+
+class Parser
+{
+public:
+    Parser(ByteBuffer::const_iterator begin, ByteBuffer::const_iterator end);
+    Parser(boost::iterator_range<ByteBuffer::const_iterator> range);
+
+    std::size_t parse_basic(BasicHeader&);
+    std::size_t parse_common(CommonHeader&);
+    std::size_t parse_secured(security::SecuredMessage&);
+    std::size_t parse_extended(HeaderVariant&, HeaderType);
+    std::size_t parsed_bytes() const;
+
+private:
+    byte_buffer_source m_byte_buffer_source;
+    boost::iostreams::stream_buffer<byte_buffer_source> m_stream;
+    InputArchive m_archive;
+    std::size_t m_read_bytes;
+};
+
+} // namespace geonet
+} // namespace vanetza
+
+#endif /* PARSER_HPP_IBDRMPKB */
+