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FLASHING.md says how to take a newer version of the colleague's tree (copy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

@@ -0,0 +1,92 @@
+#ifndef CAM_SSP_HPP_GGBE8KES
+#define CAM_SSP_HPP_GGBE8KES
+
+#include <vanetza/common/byte_buffer.hpp>
+#include <cstdint>
+#include <set>
+#include <string>
+
+namespace vanetza
+{
+namespace security
+{
+
+/**
+ * CAM permission bits
+ *
+ * These bitmasks describe CA station roles, e.g. emergency vehicles.
+ * Some CAM data containers are linked to these roles. Misuse is opposed by checking CAM SSPs.
+ *
+ * \see EN 302 637-2 V1.3.2, Table 4
+ */
+enum class CamPermission : uint16_t
+{
+    // first octet
+    CEN_DSRC_Tolling_Zone = 0x80,
+    Public_Transport = 0x40,
+    Special_Transport = 0x20,
+    Dangerous_Goods = 0x10,
+    Roadwork = 0x08,
+    Rescue = 0x04,
+    Emergency = 0x02,
+    Safety_Car = 0x01,
+
+    // second octet
+    Closed_Lanes = 0x8000,
+    Request_For_Right_Of_Way = 0x4000,
+    Request_For_Free_Crossing_At_Traffic_Light = 0x2000,
+    No_Passing = 0x1000,
+    No_Passing_For_Trucks = 0x0800,
+    Speed_Limit = 0x0400,
+    // 0x0200 and 0x0100 are reserved for future usage
+};
+
+/**
+ * Set of CAM permissions, i.e. Service Specific Permissions
+ *
+ * \see EN 302 637-2 V1.3.2, section 6.2.2.2
+ */
+class CamPermissions
+{
+public:
+    CamPermissions();
+    CamPermissions(CamPermission);
+    CamPermissions(const std::initializer_list<CamPermission>&);
+
+    // check for permission
+    bool has(CamPermission) const;
+    bool has(const std::initializer_list<CamPermission>&) const;
+    bool has(const CamPermissions&) const;
+    bool none() const;
+
+    /**
+     * Get set of all included permissions
+     * \return permission set
+     */
+    std::set<CamPermission> permissions() const;
+
+    // permission manipulation (with chaining)
+    CamPermissions& add(CamPermission);
+    CamPermissions& remove(CamPermission);
+
+    // serialization helpers
+    ByteBuffer encode() const;
+    static CamPermissions decode(const ByteBuffer&);
+
+private:
+    using value_type = std::underlying_type<CamPermission>::type;
+    value_type m_bits;
+};
+
+/**
+ * Get string representation of CAM permission flag
+ * \param cp CAM permission flag
+ * \return string representation (empty for unknown flags)
+ */
+std::string stringify(CamPermission);
+
+} // namespace security
+} // namespace vanetza
+
+#endif /* CAM_SSP_HPP_GGBE8KES */
+