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FLASHING.md says how to take a newer version of the colleague's tree (copy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

@@ -0,0 +1,41 @@
+#ifndef APPLICATION_HPP_PSIGPUTG
+#define APPLICATION_HPP_PSIGPUTG
+
+#include <vanetza/btp/data_interface.hpp>
+#include <vanetza/btp/data_indication.hpp>
+#include <vanetza/btp/data_request.hpp>
+#include <vanetza/btp/port_dispatcher.hpp>
+#include <vanetza/geonet/data_confirm.hpp>
+#include <vanetza/geonet/router.hpp>
+
+class Application : public vanetza::btp::IndicationInterface
+{
+public:
+    using DataConfirm = vanetza::geonet::DataConfirm;
+    using DataIndication = vanetza::btp::DataIndication;
+    using DataRequest = vanetza::btp::DataRequestGeoNetParams;
+    using DownPacketPtr = vanetza::geonet::Router::DownPacketPtr;
+    using PortType = vanetza::btp::port_type;
+    using PromiscuousHook = vanetza::btp::PortDispatcher::PromiscuousHook;
+    using UpPacketPtr = vanetza::geonet::Router::UpPacketPtr;
+
+    Application() = default;
+    Application(const Application&) = delete;
+    Application& operator=(const Application&) = delete;
+    virtual ~Application() = default;
+
+    virtual PortType port() = 0;
+    virtual PromiscuousHook* promiscuous_hook();
+
+protected:
+    DataConfirm request(const DataRequest&, DownPacketPtr);
+
+private:
+    friend class RouterContext;
+    vanetza::geonet::GbcDataRequest request_gbc(const DataRequest&);
+    vanetza::geonet::ShbDataRequest request_shb(const DataRequest&);
+    vanetza::geonet::Router* router_;
+};
+
+#endif /* APPLICATION_HPP_PSIGPUTG */
+