feat: implement OTA functionality and update build scripts; change upgrade link to OTA in HTML

src/ota.cpp

@@ -0,0 +1,11 @@
+#include <Arduino.h>
+#include "ota.h"
+#include <ESPAsyncWebServer.h>
+#include <ESPAsyncHTTPUpdateServer.h>
+
+ESPAsyncHTTPUpdateServer updateServer;
+
+void setupOTA(AsyncWebServer &server) {
+    updateServer.setup(&server, "/ota", "admin", "admin");
+    //updateServer.setup(&server);
+}