test=release/1.5

* CHERRY_PICK 18941, 18860: TRT fp16 support.

test=release/1.5

* CHERRY_PICK 19213: Fix BUG: Mask RCNN inference diff When using AnalysisPredictor.
    1. fix affine channel fuse pass.
    2. fix condition block op.
    3. fix merge lod tensor op bug.
    4. fix memory optim cause by reset lod op.

    test=release/1.5

* add fusion_seqpool_cvm_concat test=develop

* simplify pass, test=develop

* fix code style, test=develop

* Add call stack info during runtime and compile time
test=develop

* add warning info for CPU_NUM
test=develop

* update dygraph parallel.py
test=develop

* prune the feed op in compiler
test=release/1.5

* remove compile from PE
test=develop

* test CUDAPinnedPlace in reader
test=release/1.5

* fix REGISTER_OP_WITHOUT_GRADIENT
test=develop

* merge from develop: add tensorrt support for win test=develop

* fix warpctc dynamic library not found issue on mac and windows platform

* fix backward bug

* test=release/1.5, cherry-pick hide not_support for dygraph

* test=release/1.5, cherry-pick hide not_support for dygraph

Add path to handle 1D vector

test=release/1.5

* test=develop

* test=develop

* fix mac ci random fail
* use platform instead

test=release/1.5

replace mnist dataset url

* fix py-cpuinfo mac random fail
* differentiate version on windows

test=release/1.5

test=release/1.5

* Update lamb optimizer (#18333)

* Update lamb optimizer

* Regenerate api spec

test=release/1.5

* Give an experimental warning

test=release/1.5

* Simplify multi_box_head API in detection.py and remove assign op.

BackwardStrategy
dygraph.nn
dygraph.checkpoint

*  add cuda_is_available
test=release/1.5

* update pe reduce config
test=release/1.5

*  drop the local_exe_scopes of the previous parallel_executor
test=release/1.5

Socket can't be pickled.

test=release/1.5

* test=release/1.5, add mutigpu install check

* test=develop, refine code to use cuda_devices

* sequnce mask support max length tensor input; test=develop

* add rnn_impl.py; test=develop

* add basic gru lstm unittest; test=develop

* fix api spec; test=develop

* fix sequence_mask op bug;
test=develop
test=document_preview

* change +-*x to elmentwise_op; test=develop

* add mkl flag; test=develop

* fix rnn impl bug; test=develop

* update api spec; test=develop

* fix doc bug; test=develop

* fix lstm bugs; test=develop

test=release/1.5

* Fix the GetExpectedKernelType of add_position_encoding_op.

* Fix the doc of lstm_unit outputs in nn.py.

test=release/1.5

* fix paddle cloud role maker bug

* Revert "Cherry pick install check for multi gpu (#18245)"

This reverts commit d0219002.

* test=release/1.5, ci start

* fix default value of fluid.memory_optimize
test=release/1.5

cherry-pick for #18293

add dygraph api doc for fluidDoc and api spec

* fix slice op bug; test=develop

* fix variabel test bug; test=develop

* remove slice while true; test=develop

test=release/1.5

* refine core cmake warning and print more info
* fix comments

test=release/1.5