merge net into eth lib; ipv4 owns its IP via ipv4::init/get_ip; drop state struct in favor of eth::get_mac/ipv4::get_ip

CMakeLists.txt

@@ -4,6 +4,7 @@ add_subdirectory(util)
 add_subdirectory(w6300)
 add_subdirectory(debug_log)
 add_subdirectory(msgpack)
+add_subdirectory(eth)
 
 add_library(limen STATIC
     src/arp.cpp
@@ -13,7 +14,6 @@ add_library(limen STATIC
     src/icmp.cpp
     src/igmp.cpp
     src/ipv4.cpp
-    src/net.cpp
     src/test_handlers.cpp
     src/udp.cpp
 )
@@ -29,9 +29,9 @@ target_link_libraries(limen PUBLIC
     w6300
     debug_log
     msgpack
+    eth
     pico_stdlib
     pico_sha256
-    pico_unique_id
 )
 
 set(LIMEN_PARTITION_TABLE ${CMAKE_CURRENT_SOURCE_DIR}/partition_table.json CACHE INTERNAL "")