WIP - Update ArduinoOTA and examples with MDNS.update() calls (#5494)

* ArduinoOTA: allow use without MDNS, add MDNS.update() in handle()

* Update examples with MDNS.update() in loop

* Update CaptivePortalAdvanced.ino

Fix typo

* Update CaptivePortalAdvanced.ino

astyle

* Update Arduino_Wifi_AVRISP.ino

astyle

libraries/ESP8266WebServer/examples/AdvancedWebServer/AdvancedWebServer.ino

@@ -130,6 +130,7 @@ void setup(void) {
 
 void loop(void) {
   server.handleClient();
+  MDNS.update();
 }
 
 void drawGraph() {

libraries/ESP8266WebServer/examples/FSBrowser/FSBrowser.ino

@@ -282,4 +282,5 @@ void setup(void) {
 
 void loop(void) {
   server.handleClient();
+  MDNS.update();
 }

libraries/ESP8266WebServer/examples/HelloServer/HelloServer.ino

@@ -75,4 +75,5 @@ void setup(void) {
 
 void loop(void) {
   server.handleClient();
+  MDNS.update();
 }

libraries/ESP8266WebServer/examples/HelloServerBearSSL/HelloServerBearSSL.ino

@@ -144,4 +144,5 @@ void setup(void){
 
 void loop(void){
   server.handleClient();
+  MDNS.update();
 }

libraries/ESP8266WebServer/examples/HelloServerSecure/HelloServerSecure.ino

@@ -181,4 +181,5 @@ void setup(void) {
 
 void loop(void) {
   server.handleClient();
+  MDNS.update();
 }

libraries/ESP8266WebServer/examples/SDWebServer/SDWebServer.ino

@@ -315,4 +315,5 @@ void setup(void) {
 
 void loop(void) {
   server.handleClient();
+  MDNS.update();
 }

libraries/ESP8266WebServer/examples/WebUpdate/WebUpdate.ino

@@ -70,5 +70,5 @@ void setup(void) {
 
 void loop(void) {
   server.handleClient();
-  delay(1);
+  MDNS.update();
 }