* replace amp.use_pure_fp16 with amp.dtype and amp.level

* old api still use use_pure_fp16

* test_fuse_adamw_pass still use use_pure_fp16

* add test case tuning recompute with amp(float16,o2)

* reset new test case properties TIMEOUT 60

* set smaller value of batch_size and batch_num

* deepcopy dist_context fix _rename_input problem

* fix loss name after cast

* set tuning.enable=True and use engine._tune()

* restore some changes in _rename_input()/_rename_output()

* add self.amp_dtype for _cast_loss() in auto_parallel_amp.py

* fix insert op index in _cast_loss()