Created by: chenwhql

PR types

Function optimization

PR changes

APIs

Describe

【兼容升级】Refine set_dict related APIs:

1. Change set_dict method name to set_state_dict, add alias for compatibility

• Layer.set_dict -> Layer.set_state_dict
• DataParallel.set_dict -> DataParallel.set_state_dict
• Optimizer.set_dict -> Optimizer.set_state_dict
• LearningRateDecay.set_dict -> LearningRateDecay.set_state_dict
• _LRScheduler.set_dict -> _LRScheduler.set_state_dict

2. change stat_dict argument to state_dict, which is typo in old implementations, add decorator deprecate_stat_dict for compatibility

• Layer.set_dict(stat_dict) -> Layer.set_dict(state_dict)
• DataParallel.set_dict(stat_dict) -> DataParallel.set_dict(state_dict)
• Optimzier.load(stat_dict) -> Optimzier.load(state_dict)

3. remove Layer's load_dict, which is a deprecated API, add alias for compatibility

related cn doc PR: https://github.com/PaddlePaddle/FluidDoc/pull/2535