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FLASHING.md says how to take a newer version of the colleague's tree (copy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/security/v3/boost_geometry.cpp

@@ -0,0 +1,87 @@
+#include <vanetza/asn1/security_profile.hpp>
+#include VANETZA_ASN1_SECURITY_HEADER(PolygonalRegion.h)
+#include VANETZA_ASN1_SECURITY_HEADER(TwoDLocation.h)
+#include <vanetza/common/position_fix.hpp>
+#include <vanetza/security/v3/boost_geometry.hpp>
+
+namespace vanetza
+{
+namespace security
+{
+namespace v3
+{
+
+TwoDLocationModel make_model(const asn1::TwoDLocation& location)
+{
+    return TwoDLocationModel(location.longitude * 1e-7, location.latitude * 1e-7);
+}
+
+TwoDLocationModel make_model(const PositionFix& fix)
+{
+    return TwoDLocationModel(fix.longitude / units::degree, fix.latitude / units::degree);
+}
+
+
+TwoDLocationIterator::TwoDLocationIterator(const asn1::PolygonalRegion& region, std::size_t index) :
+    m_region(&region), m_index(index)
+{
+}
+
+void TwoDLocationIterator::increment()
+{
+    ++m_index;
+}
+
+void TwoDLocationIterator::decrement()
+{
+    --m_index;
+}
+
+void TwoDLocationIterator::advance(std::size_t n)
+{
+    m_index += n;
+}
+
+std::ptrdiff_t TwoDLocationIterator::distance_to(const TwoDLocationIterator& other) const
+{
+    return other.m_index - m_index;
+}
+
+bool TwoDLocationIterator::equal(const TwoDLocationIterator& other) const
+{
+    return m_region == other.m_region && m_index == other.m_index;
+}
+
+TwoDLocationModel TwoDLocationIterator::dereference() const
+{
+    assert(m_region != nullptr);
+    assert(m_region->list.array != nullptr);
+    assert(m_region->list.count > static_cast<decltype(m_region->list.count)>(m_index));
+    return make_model(*m_region->list.array[m_index]);
+}
+
+
+PolygonalRegionRingAdapter::PolygonalRegionRingAdapter(const asn1::PolygonalRegion& region) :
+    m_region(region)
+{
+    assert(m_region.list.array != nullptr);
+}
+
+PolygonalRegionRingAdapter::iterator PolygonalRegionRingAdapter::begin() const
+{
+    return TwoDLocationIterator(m_region, 0);
+}
+
+PolygonalRegionRingAdapter::iterator PolygonalRegionRingAdapter::end() const
+{
+    return TwoDLocationIterator(m_region, m_region.list.count);
+}
+
+std::size_t PolygonalRegionRingAdapter::size() const
+{
+    return m_region.list.count;
+}
+
+} // namespace v3
+} // namespace security
+} // namespace vanetza