Remove Secure Connection macro and add the config to wifimanager. (#961)

This adds the ability to specify if the MQTT broker connection is secure via a checkbox on the config page of WiFiManager.
Also added to the WiFiManager config page is a text box to enter the brokers TLS certificate.

In the case of using manual configuration a new macro is created MQTT_SECURE_DEFAULT.
When defined as true a secure connection will be requested and the certificate defined in user_config.h will be used.

docs/upload/portal.md

@@ -14,6 +14,9 @@ From your smartphone search for your OpenMQTTGateway wifi network and connect to
 * Select your wifi
 * Set your wifi password
 * Set your MQTT Server IP
+* Set your MQTT Server Port
+* Set the MQTT secure connection box to select whether or not the connection should be secure
+* Copy/paste the MQTT server certificate in the MQTT server cert box (only required if using a secure connection), be sure to include the `-----BEGIN CERIFICATE-----` and `-----END CERTIFICATE-----` markers  
 * Set your MQTT Server username (facultative)
 * Set your MQTT Server password (facultative)
 * Set your MQTT base topic if you need to change it (you must keep the / at the end)
@@ -55,4 +58,4 @@ build_flags =
   '-DMQTT_USER="salut"'
   '-DMQTT_PASS="atoi"'
   '-DGateway_Name="OpenMQTTGateway_ESP32_OLM_GTW"'
-```
+```