replace old ethernet library with arduino official's (v2.0.0)

Author: d-a-v

.gitmodules

@@ -16,3 +16,6 @@
 [submodule "tools/esptool"]
 	path = tools/esptool
 	url = https://github.com/espressif/esptool.git
+[submodule "libraries/Ethernet"]
+	path = libraries/Ethernet
+	url = https://github.com/arduino-libraries/Ethernet