Add extended advertising support. (#72)

Adds support for advertising and connections with coded/2M PHY's.

Adds new classes `NimBLEExtAdvertising` and `NimBLEExtAdvertisement`.
When extended advertising is enabled the original advertising classes become unavailable and the new classes must be used.

Changed some return values for advertising methods for consistency with the new classes methods.

src/NimBLEClient.h

@@ -73,6 +73,9 @@ public:
     void                                        discoverAttributes();
     NimBLEConnInfo                              getConnInfo();
     int                                         getLastError();
+#if CONFIG_BT_NIMBLE_EXT_ADV
+    void                                        setConnectPhy(uint8_t mask);
+#endif
 
 private:
     NimBLEClient(const NimBLEAddress &peerAddress);
@@ -98,6 +101,9 @@ private:
     NimBLEClientCallbacks*  m_pClientCallbacks;
     ble_task_data_t*        m_pTaskData;
     ble_npl_callout         m_dcTimer;
+#if CONFIG_BT_NIMBLE_EXT_ADV
+    uint8_t                 m_phyMask;
+#endif
 
     std::vector<NimBLERemoteService*> m_servicesVector;