feat: secondary can bus callback

include/sta/devices/stm32/can.hpp

@@ -117,6 +117,15 @@ namespace sta
      * @ingroup sta_core_stm32_can
      */
     void CanBus_RxPendingCallback();
+
+    /**
+     * @brief Interrupt handler for pending RX frames. Secondary handler.
+     *
+     * May be implemented by application.
+     *
+     * @ingroup sta_core_stm32_can
+     */
+    void CanBus_RxPendingCallbackSecondary();
 #endif // STA_STM32_CAN_GLOBAL
 } // namespace sta