setKeepAlive function added issue #153 (#170)

Co-authored-by: Allen Benter <allen.benter@dpi.nsw.gov.au>

src/HAMqtt.cpp

@@ -183,6 +183,11 @@ bool HAMqtt::isConnected() const
     return _mqtt->connected();
 }
 
+void HAMqtt::setKeepAlive(uint16_t keepAlive)
+{
+    _mqtt->setKeepAlive(keepAlive);
+}
+
 void HAMqtt::addDeviceType(HABaseDeviceType* deviceType)
 {
     if (_devicesTypesNb + 1 > _maxDevicesTypesNb) {

src/HAMqtt.h

@@ -202,6 +202,11 @@ public:
      * Returns true if connection to the MQTT broker is established.
      */
     bool isConnected() const;
+    
+    /**
+     * sets keepAlive value.
+     */
+    void setKeepAlive(uint16_t keepAlive);
 
     /**
      * Adds a new device's type to the MQTT.
@@ -389,4 +394,4 @@ private:
     bool _lastWillRetain;
 };
 
-#endif
+#endif