chore: add benchmark and tests for GetManagedObjects (#150)

bench/unmarshall_getmanagedobjects.py

@@ -0,0 +1,25 @@
+import io
+import timeit
+
+from dbus_fast._private.unmarshaller import Unmarshaller
+
+#  cythonize -X language_level=3 -a -i  src/dbus_fast/_private/unmarshaller.py
+
+with open("tests/data/get_managed_objects.hex") as fp:
+    msg = fp.read()
+
+
+stream = io.BytesIO(bytes.fromhex(msg))
+
+unmarshaller = Unmarshaller(stream)
+
+
+def unmarhsall_bluez_get_managed_objects_message():
+    stream.seek(0)
+    unmarshaller.reset()
+    unmarshaller.unmarshall()
+
+
+count = 10000
+time = timeit.Timer(unmarhsall_bluez_get_managed_objects_message).timeit(count)
+print(f"Unmarshalling {count} bluetooth GetManagedObjects messages took {time} seconds")