add localhost 'network' library test

res/scripts/world.lua

@@ -1,3 +1,25 @@
 -- use for engine development tests
 -- must be empty in release
 -- must not be modified by content-packs
+
+local server = network.tcp_open(65343, function (socket)
+    print("connected client", socket.id)
+    socket:send(utf8.tobytes("Hello, World!"))
+    socket:close()
+end)
+print("server", server.id)
+
+local socket = network.tcp_connect('localhost', 65343, function (socket)
+    print("connected", socket.id)
+end)
+
+function on_world_tick()
+    local result = socket:recv(128)
+    if result and #result > 0 then
+        print("received from server:", utf8.tostring(result)) 
+    end
+end
+
+function on_world_quit()
+    server:close()
+end