more lwIP physical interfaces (#6680)

This commit adds W5500 W5100 and ENC28j60 drivers from @njh with credits
They are available in libraries/
An example is added in W5500 examples directory

plus:
* Extract dhcp server from lwip2 and add it to the core as a class.
  It must always be present, it is linked and can be called by fw on boot.
  So it cannot be stored in a library.
* ethernet: static or dhcp works
* PPPServer: example
* bring WiFi.config() to the lwIP generic interface (argument reorder common function)
* move hostname() from WiFI-STA to generic interface
* remove non readable characters from dhcp-server comments
* dhcp-server: magic_cookie is part of bootp rfc
* fixes from https://github.com/d-a-v/W5500lwIP/issues/17
* enable lwip_hook_dhcp_parse_option()
* +ethernet tcp client example in w5500 library examples

tools/sdk/lwip2/include/lwip/priv/tcp_priv.h

@@ -357,7 +357,7 @@ extern struct tcp_pcb ** const tcp_pcb_lists[NUM_TCP_PCB_LISTS];
 #if TCP_DEBUG_PCB_LISTS
 #define TCP_REG(pcbs, npcb) do {\
                             struct tcp_pcb *tcp_tmp_pcb; \
-                            LWIP_DEBUGF(TCP_DEBUG, ("TCP_REG %p local port %"U16_F"\n", (void *)(npcb), (npcb)->local_port)); \
+                            LWIP_DEBUGF(TCP_DEBUG, ("TCP_REG %p local port %" U16_F "\n", (void *)(npcb), (npcb)->local_port)); \
                             for (tcp_tmp_pcb = *(pcbs); \
           tcp_tmp_pcb != NULL; \
         tcp_tmp_pcb = tcp_tmp_pcb->next) { \