fix(net): Add back the friend classes required for Ethernet.h to work

Author: me-no-dev

Diff for: cores/esp32/IPAddress.h

@@ -124,6 +124,9 @@ class IPAddress : public Printable {
   friend class UDP;
   friend class Client;
   friend class Server;
+  friend class EthernetClass;
+  friend class DhcpClass;
+  friend class DNSClient;
 
 protected:
   bool fromString4(const char *address);