Allow for hiding mqtt config settings in wifimanager setup. (#1049)

* Allow for hiding mqtt config settings in wifimanager setup.

Adds the macro `WIFIMNG_HIDE_MQTT_CONFIG` that when defined will hide the mqtt configuration in the wifimanager setup.

Co-authored-by: Florian <1technophile@users.noreply.github.com>

main/User_config.h

@@ -109,6 +109,7 @@ const byte mac[] = {0xDE, 0xED, 0xBA, 0xFE, 0x54, 0x95}; //W5100 ethernet shield
 #ifndef WM_DEBUG_LEVEL
 #  define WM_DEBUG_LEVEL 1 // valid values are: DEBUG_ERROR = 0, DEBUG_NOTIFY = 1, DEBUG_VERBOSE = 2, DEBUG_DEV = 3, DEBUG_MAX = 4
 #endif
+//#define WIFIMNG_HIDE_MQTT_CONFIG //Uncomment so as to hide MQTT setting from Wifi manager page
 
 /*-------------DEFINE YOUR ADVANCED NETWORK PARAMETERS BELOW----------------*/
 //#define MDNS_SD //uncomment if you  want to use mdns for discovering automatically your ip server, please note that MDNS with ESP32 can cause the BLE to not work