Use HTTP method table from ESP-IDF's nghttp (#4900)

Fixes: #4884

* Use HTTP method table from ESP-IDF's nghttp
* Parse methods using IDF's HTTP method list
* Make example's loops to allow the CPU to switch tasks

libraries/WebServer/examples/AdvancedWebServer/AdvancedWebServer.ino

@@ -125,6 +125,7 @@ void setup(void) {
 
 void loop(void) {
   server.handleClient();
+  delay(2);//allow the cpu to switch to other tasks
 }
 
 void drawGraph() {