feat(udp): Allow to change the async_udp task stack size

Example:  `-D CONFIG_ARDUINO_UDP_TASK_STACK_SIZE=2048`
The default is to much conservative since a correctly developed app probably won't allocate too much on stack on the callbacks. I currently see a wast of memory:
`I (1222501) MONITOR: async_udp  (p=3) 3416 bytes`

Author: mathieucarbou

Kconfig.projbuild

@@ -147,6 +147,12 @@ config ARDUINO_UDP_TASK_PRIORITY
     help
         Select at what priority you want the UDP task to run.
 
+config ARDUINO_UDP_TASK_STACK_SIZE
+    int "UDP task stack size"
+    default 4096
+    help
+        Amount of stack available for the UDP task.
+
 config ARDUINO_ISR_IRAM
     bool "Run interrupts in IRAM"
     default "n"

libraries/AsyncUDP/src/AsyncUDP.cpp

@@ -189,7 +189,7 @@ static bool _udp_task_start() {
   }
   if (!_udp_task_handle) {
     xTaskCreateUniversal(
-      _udp_task, "async_udp", 4096, NULL, CONFIG_ARDUINO_UDP_TASK_PRIORITY, (TaskHandle_t *)&_udp_task_handle, CONFIG_ARDUINO_UDP_RUNNING_CORE
+      _udp_task, "async_udp", CONFIG_ARDUINO_UDP_TASK_STACK_SIZE, NULL, CONFIG_ARDUINO_UDP_TASK_PRIORITY, (TaskHandle_t *)&_udp_task_handle, CONFIG_ARDUINO_UDP_RUNNING_CORE
     );
     if (!_udp_task_handle) {
       return false;