Add context argument to sl_zigbee_af_event_t

[Xeenych]

In order to interact with high-level code it will be very useful to add void* dtaCtx field to sl_zigbee_af_event_t struct as shown:

event-queue.h

typedef struct Event_s {
.....
  // Owned by the end user
  void *dataPtr;                        // a generic pointer
  void *dataCtx;
} sli_zigbee_event_t;

then in sl_zigbee_system_common.h line 186 add void* parameter to function signature:

void sli_zigbee_af_event_internal_init(sl_zigbee_af_event_t *event,
                                       const char *event_name,
                                       void *handler,
                                       uint8_t network_index,
                                       uint8_t endpoint,
                                       void *ctx) {
.....
  event->dataCtx = ctx;
}

and on lines 175-179:

 if (is_endpoint_event) {
    ((void (*)(uint8_t))(event->dataPtr))(sli_zigbee_af_event_get_endpoint(event));
  } else {
    ((void (*)(sl_zigbee_af_event_t *, void *))(event->dataPtr))(event, event->dataCtx);
  }

then in zigbee_app_framework_event.h on lines 136-143 add NULL as last parameter:

#if (SL_ZIGBEE_EVENT_DEBUG_ENABLED)
  #define sl_zigbee_af_event_init(event, handler) \
  sli_zigbee_af_event_internal_init((event), (#event), (void *)(handler), 0xFF, 0xFF, NULL)
#else
  #define sl_zigbee_af_event_init(event, handler) \
  sli_zigbee_af_event_internal_init((event), NULL, (void *)(handler), 0xFF, 0xFF, NULL)
#endif // SL_ZIGBEE_EVENT_DEBUG_ENABLED
#endif // DOXYGEN_SHOULD_SKIP_THIS