fix(esp_http_server): Async handler example stack overflow fix

1. In async handler example, on hitting /long URI and closing the
connection forcefully from client (example ctrl + c) cause more stack
size (almost 200 bytes) than successfull request.
2. The connection should be closed from the server as soon as the client
closes the connect (i.e. handler should return ESP_FAIL to close the
connection)

examples/protocols/http_server/async_handlers/main/Kconfig.projbuild

@@ -7,4 +7,10 @@ menu "Example Configuration"
             The maximum number of simultaneous async requests that the
             web server can handle.
 
+    config EXAMPLE_ASYNC_WORKER_TASK_STACK_SIZE
+        int "Async Worker Task Stack Size"
+        default 2560
+        help
+            The stack size allocated for each async worker task.
+
 endmenu