Add vendored cloudpickle.

Author: claudevdm

sdks/python/apache_beam/internal/cloudpickle/__init__.py

@@ -0,0 +1,18 @@
+from . import cloudpickle
+from .cloudpickle import *  # noqa
+
+__doc__ = cloudpickle.__doc__
+
+__version__ = "3.2.0.dev0"
+
+__all__ = [  # noqa
+    "__version__",
+    "Pickler",
+    "CloudPickler",
+    "dumps",
+    "loads",
+    "dump",
+    "load",
+    "register_pickle_by_value",
+    "unregister_pickle_by_value",
+]