BLE: Show name of device which is connected / is trying to pair

Tries to read the device name of the central via the GAP Device Name characteristic. If there is a device name available, it will be shown on the screen. Even if it only becomes available at a later time during pairing.

This is how it looks now:

epicardium/ble/profiles/gap_api.h

+/*************************************************************************************************/
+/*!
+ *  \file
+ *
+ *  \brief  GAP profile.
+ *
+ *  Copyright (c) 2015-2018 Arm Ltd. All Rights Reserved.
+ *  Arm Ltd. confidential and proprietary.
+ *
+ *  IMPORTANT.  Your use of this file is governed by a Software License Agreement
+ *  ("Agreement") that must be accepted in order to download or otherwise receive a
+ *  copy of this file.  You may not use or copy this file for any purpose other than
+ *  as described in the Agreement.  If you do not agree to all of the terms of the
+ *  Agreement do not use this file and delete all copies in your possession or control;
+ *  if you do not have a copy of the Agreement, you must contact Arm Ltd. prior
+ *  to any use, copying or further distribution of this software.
+ */
+/*************************************************************************************************/
+#ifndef GAP_API_H
+#define GAP_API_H
+
+#include "att_api.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*! \addtogroup GAP_PROFILE
+ *  \{ */
+
+/**************************************************************************************************
+  Macros
+**************************************************************************************************/
+
+/*! \brief Enumeration of handle indexes of characteristics to be discovered */
+enum
+{
+  GAP_DN_HDL_IDX,
+  GAP_CAR_HDL_IDX,          /*!< \brief Central Address Resolution */
+  GAP_RPAO_HDL_IDX,         /*!< \brief Resolvable Private Address Only */
+  GAP_HDL_LIST_LEN          /*!< \brief Handle list length */
+};
+
+/**************************************************************************************************
+  Function Declarations
+**************************************************************************************************/
+
+int GapGetDeviceName(char *buf, size_t buf_size);
+void GapClearDeviceName(void);
+
+/*************************************************************************************************/
+/*!
+ *  \brief  Perform service and characteristic discovery for GAP service.  Note that pHdlList
+ *          must point to an array of handles of length \ref GAP_HDL_LIST_LEN.  If discovery is
+ *          successful the handles of discovered characteristics and descriptors will be set
+ *          in pHdlList.
+ *
+ *  \param  connId    Connection identifier.
+ *  \param  pHdlList  Characteristic handle list.
+ *
+ *  \return None.
+ */
+/*************************************************************************************************/
+void GapDiscover(dmConnId_t connId, uint16_t *pHdlList);
+
+/*************************************************************************************************/
+/*!
+ *  \brief  Process a value received in an ATT read response, notification, or indication
+ *          message.  Parameter pHdlList must point to an array of length \ref GAP_HDL_LIST_LEN.
+ *          If the attribute handle of the message matches a handle in the handle list the value
+ *          is processed, otherwise it is ignored.
+ *
+ *  \param  pHdlList  Characteristic handle list.
+ *  \param  pMsg      ATT callback message.
+ *
+ *  \return \ref ATT_SUCCESS if handle is found, \ref ATT_ERR_NOT_FOUND otherwise.
+ */
+/*************************************************************************************************/
+uint8_t GapValueUpdate(uint16_t *pHdlList, attEvt_t *pMsg);
+
+/*! \} */    /* GAP_PROFILE */
+
+#ifdef __cplusplus
+};
+#endif
+
+#endif /* GAP_API_H */