Enable connection with encryption without certificate validation (#1386)

* Enable connection with encryption without certificate validation
* Add the cert validation for AWS env

platformio.ini

@@ -473,6 +473,7 @@ build_flags =
   '-DLED_SEND_RECEIVE_ON=0'
   '-DMQTT_SECURE_DEFAULT=true'
   '-DMQTT_SECURE_SELF_SIGNED'
+  '-DMQTT_CERT_VALIDATE_DEFAULT=true'
   '-DMQTT_SERVER="xxxxxxxxxxxxx-ats.iot.eu-west-2.amazonaws.com"'
   '-DMQTT_PORT="8883"'
   '-DMQTT_USER=""'