add more interface for user in common_ops_import (#44270)

python/paddle/common_ops_import.py

@@ -14,7 +14,7 @@
 from six.moves import reduce
 from paddle.fluid.layer_helper import LayerHelper
 from paddle.fluid.param_attr import ParamAttr
-from paddle.fluid.framework import convert_np_dtype_to_dtype_, _non_static_mode, _varbase_creator
+from paddle.fluid.framework import convert_np_dtype_to_dtype_, _non_static_mode, _varbase_creator, in_dygraph_mode, _in_legacy_dygraph
 from paddle.fluid.framework import device_guard, default_main_program, dygraph_only, _dygraph_tracer
 from paddle.fluid.framework import OpProtoHolder, Variable
 from paddle.fluid.initializer import Constant