* add cast ops before and after unsupported fp16 ops.

* Keep partial net in FP32 pattern.

* Support check_finite_and_unscale and update_loss_scaling for FP16 calculation mode.

* Add fp16 support for adam op.

* add multi precision attr for adam.

* Fix the bug of test_multi_precision_fp16_train UT.

* Code format for CI.

* Fix the redefine error about MPTypeTrait on windows.

* fix bugs of the _create_accumulators func in Momentum.

* fix bug when inserting post cast op.

* Add the update_loss_scaling op in allow_set of UnusedVarCheck.

* Update for ci coverage.

* Add some doc for OptimizerWithMixedPrecision.

* Fix the code style.

* Imporve the doc of `amp_init`.

* Change for fp16 testing if users have the infer program defined in separate way.

* fix dtype of ungenerated grad var

* update ut

* refine code

* set default dtype

* fix could_use_cudnn bug

* remove debug code

* re-implement

* fix bug

* fix tensor shape bug

* fix op_num

* clean code

In creation.assgin, reuse implamention code of layers.tensor.assign to avoid maintain two code (#30227)

1. When x is Variable, call nn.shape(x) only in following cases:
 1）The shape of x is used in control flow condition.
 2）The dim to be used is negetive
2. When x is Variable, but x.shape or x.shape[idx] doesn't contain negetive value, don't convert to paddle.shape()

* change to tensor copy sync

* change to tensor copy sync

* make copy_to safe when use TensorCopy

* refine code

* add ut

* add cudapinned garbagecollector

* add testcase: cpu place -> cuda pinned place

In control flow, don't copy TensorArray from subblock to parent block when TensorArray is created in parent block.

* add tensor table

* Quantization supports 2.0 APIs

* Fix the error of save_quantized_model

* Add a necessary condition

* Remove test for white list and add header

* enhance error message of nll_loss op test=develop

Improve some error messages in parallel_executor.cc, conditional_block_op.cc, recurrent_op.cc

* simplify prepared op impl to improve performance

* fix kunlun compile error

* continue fix kunlun compile error

* only transform diff place when dtype diff

* fix failed unittests

* remove useless file

* polish impl by review comment

* test=develop, add index_select_cuda kernel

* enhance error info for py_func

* update

[XPU] Remove lite_xpu ut lite_resnet50_test since fusion pass changes introduced precision diff. test=develop (#30122)

* Simplify the options of spawn based on fleetrun

* polish details

* polish doc details

Change-Id: Ia5279b0cbb6a5b3970aff66e9510e0d85efa70ce

* test=develop, add model_average and lookahead

* fix syncbn convet

* add unittest

* add dispenable input 'shape' for core.ops.reshape2

* add dispenable inputs for core.ops.reshape2/expand/slice

* add ut