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FLASHING.md says how to take a newer version of the colleague's tree (copy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

@@ -0,0 +1,101 @@
+#include "station.hpp"
+#include "certificate.hpp"
+#include "hashed_id8.hpp"
+#include "hashed_id8_validator.hpp"
+#include <functional>
+#include <iostream>
+
+namespace vanetza
+{
+namespace pki
+{
+
+namespace
+{
+
+const HashedId8Validator hid8_validator;
+
+struct Context
+{
+    Context(const MainConfig& c) : cfg(c)
+    {
+    }
+
+    const MainConfig& cfg;
+    std::function<void()> action;
+    std::string canonical;
+    HashedId8 root_ca;
+};
+
+void print_station_summary(Context& ctx)
+{
+    const std::string canonical = ctx.cfg.station->get_canonical_identifier();
+    const boost::optional<HashedId8> ec_id = ctx.cfg.station->get_ec_identifier();
+    const boost::optional<HashedId8> root_ca = ctx.cfg.station->get_root_ca();
+
+    std::cout << "Canonical identifier: " << (canonical.empty() ? "[unknown]" : canonical) << "\n";
+    std::cout << "Enrolled: " << (ec_id ? "yes" : "no") << "\n";
+    if (ec_id) {
+        std::cout << "EC digest: " << hexstring(*ec_id) << "\n";
+        boost::optional<Certificate> ec_cert = ctx.cfg.enrolment_credentials->fetch(*ec_id);
+        std::cout << "EC certificate: " << (ec_cert ? "[available]" : "[missing]") << "\n";
+    }
+
+    if (root_ca) {
+        std::cout << "Root CA: " << hexstring(*root_ca) << "\n";
+        boost::optional<std::string> dc_url = lookup_dc_url(ctx.cfg.data_path / "ectl.ctl", *root_ca);
+        if (dc_url) {
+            std::cout << "DC URL: " << *dc_url << "\n";
+        } else {
+            std::cout << "DC URL: [not found in ECTL]\n";
+        }
+    } else {
+        std::cout << "Root CA: [not set]\n";
+    }
+}
+
+void set_root_ca(Context& ctx)
+{
+    if (auto cert = ctx.cfg.root_ca->fetch(ctx.root_ca)) {
+        if (is_root_ca(*cert)) {
+            ctx.cfg.station->set_root_ca(ctx.root_ca);
+            std::cout << "Found Root CA certificate in cache.\n";
+        } else {
+            std::cout << "Found certificate matching " << hexstring(ctx.root_ca)
+                      << ", but it is not a Root CA certificate!\n";
+        }
+    } else {
+        std::cout << "Cannot set Root CA because the full certificate is missing.\n";
+    }
+}
+
+} // namespace
+
+std::shared_ptr<CLI::App> build_station_command(const MainConfig& cfg)
+{
+    auto ctx = std::make_shared<Context>(cfg);
+    auto app = std::make_shared<CLI::App>("summary of station configuration", "station");
+
+    auto set_canonical = app->add_subcommand("set-canonical-id", "set the canonical identifier");
+    set_canonical->add_option("id", ctx->canonical, "canonical identifier")->required();
+    set_canonical->callback([ctx]() {
+        ctx->action = [ctx]() { ctx->cfg.station->set_canonical_identifier(ctx->canonical); };
+    });
+
+    auto set_root = app->add_subcommand("set-root-ca", "set the station's Root CA");
+    set_root->add_option("hid8", ctx->root_ca, "HashedId8 of the Root CA")->required()->check(hid8_validator);
+    set_root->callback([ctx]() { ctx->action = [ctx]() { set_root_ca(*ctx); }; });
+
+    app->require_subcommand(0, 1);
+    app->final_callback([ctx]() {
+        if (!ctx->action) {
+            ctx->action = [ctx]() { print_station_summary(*ctx); };
+        }
+        ctx->action();
+    });
+
+    return app;
+}
+
+} // namespace pki
+} // namespace vanetza