* Change the api of DataParallel and Fleet (#29224)

Cherry-pick of PR #29226

* The leaf tensor concept is exposed and the gradient accumulation of leaf tensor

* The leaf tensor concept is exposed and the gradient accumulation of leaf tensor

* fix coverage

* fix api doc

* fix CI unittest

* fix CI unittest

* fix unitest

* empty tensor does’t need inner_var_

* fix some error message

* Add a class TensorInplaceVersion to count the inplace version and put it in framework::Tensor instead of Allocation or Variable.

* Add a new attribute `_inplace_version` for VarBase.

* Raise exception if an inplace operation can result in incorrect gradient computation.

* Add a new interface _bump_inplace_version() for VarBase to bump the version whenever the Tensor is modified through an inplace operation.

* For api assign, call _bump_inplace_version() when it's an inplace operation inn dynamic mode.

* Use original var_wrapper if the inplace_version is not changed.

* Replace SnapshotVarWrapperList with SnapshotVarWrapper to optimize performane.

* Changed a variable name error

* Add comments

* Move member functions of TranslatedLayer out of function

* edit code according to review

* Edit input argument of '_run_static_graph'

* reset due to Segmentation fault

* rename variables when stitching graph

* modify code according CI

* Add comments to '__i_m_p_l__'

* remove blanks befor 'Get...'

* edit code according to review

* Add a comment to '_execution_method_creator'

* Edit a comment to '_execution_method_creator'

[Dy2Stat] Fix bug: the return statement should be transformed to an equivalent Paddle/Python if statement, which depends on if conditions of the return stmt. (#29165)

* add reducer

* refine envent for memorycopy

* add concat&split for allreduce

* apply concat & split for fuse tensor

* fix nccl dep

* fix the untest, compile problem and ddp initialize problem

* fix untest for mac & add some comments & solve the repeated param in sublayers

* fix untest for windows & fix document

[Dynamic-to-Static] Support **kwargs as input of the function which is decorated by `jit.save.to_static` (#29098)

* split train_mode and has_grad

* fix format

* fix ci problems

* fix sample code

* Rename variables when use 'jit.load'

* Check whether the original graph contains the variable with the same name

* add comment

* rename output/input of op and edit unittest

* modify the code according to CI

* edit code according to CI

* edit code according to CI

* edit code according to CI

* edit code according to CI

* edit code according to CI

* edit code according to CI

* Support pop for dict in dy2stat

* Move convert_pop to convert_operators.py and polish convert_pop

* polish parallel api impl & doc details

* add unittest for coverage

* remove spawn test in py2.7

* add parallel api into white list

* fix some docs test=develop;test=document_fix

* add code example test=develop;test=document_fix

* fix code example test=develop;test=document_fix

* fix code example test=develop;test=document_fix

* fix code example test=develop;test=document_fix

Add support for using tuple as tensor.shape (For example: a, b, c, d = x.shape)

* upgrade comment string to raw string

* fix string in

* fix string with ' '

* revert update on comments

* upgrade only necessary

* fix sample code checker

* fix comments with '''

[Dynamic-to-Static] Fix bug of convert_logical_and/convert_logical_or: the operands are executed sequentially(#28993)

  
  1) The operands are executed sequentially according to the running logic of Python.
  
  2) If the left hand operand is True(for convert_logical_or)/False(for convert_logical_and), the right hand operand should be executed.

The PR description is long. See details in the PR link.

* fix eng doc, test=develop

* add import deprecated for layers, test=develop

* add block line for doc generate, test=develop

* remove todo for create_variable, test=develop

* add blank line for doc generate, test=develop

* add blank line for doc generate, test=develop

[Dynamic-to-Static] Fix bug in loop_transformer: loop vars should contain the var from ancestor-for-node (#28735)

[Dynamic-to-Static ErrorMessage] Support dy2stat error message when call jit.save and polish error message (#28713)

* Support dy2stat error message when call jit.save;

* Polish dy2stat error message:
  (1) the original dygraph code is marked with (* user code *) ; 
  (2) "In user code:" -> "In transformed code:"

Fix convert_callmMay be called multiple times in Dy2stat. Also strip some strings to make sure no influence from blank spaces.

* add matmtl_v2 to amp list

* support dygraph

Fix a bug that used in PaddleGAN model which used `isinstance` in a for loop

also fix `no_grad` alias

1. Remove 'fluid';
2. Variable -> Tensor

APIs:
 sum, convert_call, convert_ifelse,
 convert_logical_and, convert_logical_or, convert_logical_not

Modify ProgramTranslator and TracedLayer Doc for API 2.0

Remove "fluid", "variable" in 2.0 API doc

* refine jit.save/load to add support for other method, not only forward

* refine the code based on unit tests

* Add unit test for the code

* Add unit test for the code

* Modify the code according to the unit test

* Delete useless comments, save only one info file, etc.

* remove static_mode_white_list.pyc

* edit the code that generate 'extra_var_info'

* Fix bug in convert_call

* refine unittest

* refine code

* refine code

* fix unittest failed

* add assert