* add return when input is tensor

* fix typo

* add private api for memcpy_op

* change place dtype

* add private python api for memcpy op

* fix stop_gradient in paddle.to_tensor

* make to_tensor copy if data is varbase

* add ut

* refine sample code

add __all__=[] to python files not in API public list; import * only support in API public list files (#32643)

A follow up PR of #32420, we changed the doc of python/paddle/fluid/layers/tensor.py in that PR and we are changing python/paddle/tensor/creation.py in this PR.

paddle.to_tensor will be translated to paddle.assign in Dy2stat, however paddle.assign doesn't support int, float, bool. This PR added the supports.

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

* rm complexvariable

* modify test_var_base unittest

* remove duplicated codes

* 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 '''

* transfer from paddle.fluid.layers.assign() into creation.py,test=develop

* fix ut fail,add support for paddle.assign,test=develop

* fix,test=develop

* fix UT coverage,test=coverage

* fix UT fail,test=coverage

* fix doc,test=develop

* modify cond while_loop to paddle.static.nn.cond

* modify crop_tensor to paddle.crop

* modify Variable to paddle.static.Variable

* remove nn.beam_search, nn.beam_search_decode, nn.gather_tree

* remove bpr_loss, center_loss, rank_loss, smooth_l1, teacher_student_sigmoid_loss, edit_distance, sampled_softmax_with_cross_entropy in nn.functional

* remove apis in nn.functional.learn_rate.py

* remove pool2d, pool3d, adaptive_pool2d, adaptive_pool3d in nn.functional

* remove apis in nn.functional.vision

* remove erf, soft_relu in nn.functional.activation

* remove apis in nn.functional.extension

* remove nn.functional.rnn

* remove hash from nn.functional.lod

* remove row_conv from nn.functional.extension

* remove one_hot, pad2d, pad_constant_like from nn.functional.common

* remove nn.gather_tree, nn.BilinearTensorProduct, nn.Pool2D, nn.Pad2D

* remove apis from optimizer.__init

* remove tensor.creation.fill_constant

* remove elementwise_mul in nn.functional.common and  modify to paddle.multiply

* remove  tensor.stat.reduce_mean

* remove reduce_all, reduce_any in tensor.logic

* remove apis in tensor.math

* remove apis in tensor.__init__

* remove has_inf, has_nan in tensor.search

* remove apis in framework.__init__

* remove apis in paddle.__init__

* remove apis in nn.functional.__init__

* modify removed alias apis to raw api in doc and unittests

* fix remove grid_sample bug

* modify removed alias apis to raw api in doc and unittests

* modify removed alias apis to raw api in doc and unittests

* modify removed alias apis to raw api in doc and unittests

* modify removed alias apis to raw api in doc and unittests

* modify removed alias apis to raw api in doc and unittests

* modify removed alias apis to raw api in doc and unittests

* delete alias api relastions in doc

* reserve paddle.compat, paddle.sysconfig

* remove unittest for paddle.reduce_all, paddle.reduce_any

* modify removed alias apis to raw api in doc and unittests

* recover paddle.save and paddle.load

* resolve conflicts

* fix sample code missing paddle.enable_static() bug

* fix sample code missing paddle.enable_static() bug

* fix to_string sample code error

and optimize the c++ implmentation of empty op as PR#26659 reviews,
and add bool for shape op.

* temporally disable zero_copy

* add test

* follow comments

update doc of paddle.to_tensor

* set_default_type only take effect on python floats or complex

* fix doc

* add set_default_type for tensor

* fix doc

* fix doc

add parameters check in static mode for diag op 

add paddle.tensor.linalg.diag API, diag_v2 OP and CUDA kernel.

* expose and unify the Tensor concepts to the user

* expose tensor to user

* add copy place for Tensor

* add copy place for Tensor

* add note

* add macro PADDLE_WITH_CUDA

* remove RUN_TYPE=DIST

* fix some error

* fixed imperative module in doc example code

* fixed static module

* solve conflict