ADD: add performance measure example

Author: T-K-233

examples/echo_client_perf.py

@@ -0,0 +1,19 @@
+import time
+
+from cc.udp import UDP
+
+
+udp = UDP(recv_addr=("0.0.0.0", 8001), send_addr=("127.0.0.1", 8000))
+
+counter = 0
+
+udp.send("Hello, World: {counter}".encode())
+
+while True:
+    t = time.perf_counter()
+    for i in range(1000):
+        data = udp.recv()
+        counter += 1
+        udp.send(f"Hello, World: {counter}".encode())
+    print(f"Round trip time: {time.perf_counter() - t:.4f} ms")
+