* Add rnn_op.
test=develop

* Fix rnn_op grad maker's drop_empty_grad.
test=develop

This PR is follow up of #28213. On that PR we tried to decrease GPU usage, however the CI still randomly failed. So I added retry logic for the initialization of nccl and cusolver. If the initialization failed, we can retry to avoid the random failure.

* add generate_proposals_v2 op

* Fix lr setting of AdamW when lr is an instance of LRScheduler.
test=develop

* Fix static graph test mode in test_adamw_op.py.
test=develop

* [Dy2stat] Support to modify value of buffer tensor

* remove "defaultTest"

* fix name confliction

* update version pybind to v2.4.3, test=develop

* update unittests, test=develop

* check and fix tensor and scalar type promotion

* fix else branch error

* fix scalar method error

* fix test_math_op_path unittest

* add future division for unittest

* rm useless bin file

* return pil image as default according backend

* Add median api.

* Add median api.

* Add median api.

* Add median api.

* Add median api.

* enable infer model running CAPI

* output size should bigger than 0

* add op_function_generator for box_coder

* fix format

* 01:Modify the shell script according to the specification

* 01:Modify the shell script according to the specification

* enable test_parallel_executor_fetch_isolated_var, test=develop

* add enable_static, test=develop

* set test_parallel_executor_fetch_isolated_var RUN_TYPE=DIST, develop=test

* Enhance multiclass_nms to support LoD for dygraph mode

* fix some error in multiclass_nms

* update GetLodFromRoisNum to GetNmsLodFromRoisNum

* fix lr scheduler

* fix code style

* add + - * / @ [] operator to ComplexVariable, also add unittest

* fix circular reference bug

* fit for py2.7

* remove reverse oprators which not supported now

fix dygraph gather api 

* set static shape for shape tensor with constant

* remove debug code

* fix typo

* add ut

* refine code

* refine example

* fix fleetrun heter ps on paddlecloud

* fix AMP auto_cast and grad_scaler En doc

* fix indentation problem

* change Conv2d to Conv2D

test=develop

* fix judge bug of errorlevel

* fix some error

* update matrix nms op to api 2.0

* modify code according to review

[Dy2Stat-log] Call warnings.warn() to display the warning-message only once when calling StaticFunc.__call__ or ProgramTranslator().get_output (#28260)