[AMP] Add python API for collecting operator stats.

[Xreki]

PR types

Others

PR changes

APIs

Describe

工作内容1：添加动态图算子数据类型、调用次数统计的正式Python API，包括两组API：

1. 一对enable/disable来开启、关闭算子统计功能：paddle.amp.debugging.enable/disable_operator_stats_collection
2. 一个上下文切换API：paddle.amp.debugging.collect_operator_stats

使用示例和效果如下：

import paddle
conv = paddle.nn.Conv2D(3, 2, 3)
x = paddle.rand([10, 3, 32, 32])
paddle.amp.debugging.enable_operator_stats_collection()
# AMP list including conv2d, elementwise_add, reshape2, cast (transfer_dtype)
with paddle.amp.auto_cast(enable=True, level='O2'):
    out = conv(x)
# Print to the standard output.
paddle.amp.debugging.disable_operator_stats_collection()
# <------------------------------------------------------- op list -------------------------------------------------------->
# <--------------- Op Name ---------------- | -- FP16 Calls --- | -- BF16 Calls --- | --- FP32 Calls--- | -- Other Calls -->
#   conv2d                                  |  1                |  0                |  0                |  0
#   elementwise_add                         |  1                |  0                |  0                |  0
#   reshape2                                |  1                |  0                |  0                |  0
#   transfer_dtype                          |  0                |  0                |  3                |  0
# <----------------------------------------------------- op count: 4 ------------------------------------------------------>

工作内容2：添加test/amp子目录，放置AMP功能相关的单测。

三个API的英文文档预览如下：

• collect_operator_stats
  

• enable_operator_stats_collection
  

• disable_operator_stats_collection
  

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[AnnaTrainingG]

Good

[XieYunshen]

LGTM for 单测重命名