Python Unit Tests for CSP

* Simple Channel Send and Receive test
* Daisy Chain test with 100 channels/Go ops

* Adding Python boilerplate code for Go op

* Add very basic test case

* Adding the python logic for go routine

* Fix syntax

* Changing test to notest

* Rename Routine to Go

* Combining GoGuard and Go in one class

* Modify test

* Adding fluid close channel

* Fixing __init__.py for calling fluid.go()

* Adding stubs for channel methods and updating test case

* Removing import *

* Adding imports from concurrency

* Initial commit of GO_OP (for varun)

* Creating local scopes and go through them

* Updated go op inputs persistability enforcement

* Add thread execution; compile failing though

* Fix go op

* Cleaned up Go op

* Fix yapf format issue

* Readd warp ctc dir for unit tests

* Updated make_channel, channel_send, channel_recv and channel_close

* Moved thread function to another method, update unit tests

* remove output var

* Add stubs for channel operators

* Updating concurrency with signatures

* Updated the signature with return status

* Fixed dtype in variables

* Updating stub of ChannelSend + add infershape

* Updating stub of ChannelRecv + add infershape

* Updated signature

* Adding the channel_create operator

* Merge channel send+receive ops

* Update concurrency tests using all operators

* Updating the create op with ChannelHolder

* Fix issues with channel_create_op

* Add the implementation for channel_close op

* Add channel close operator, fix channel close op

* Adding the channel_send op

* Comment channels C++ and Python code

* Concurrency python api comment fix

* Update unit test to add Status variable

* Adding channel receive operator

* Update concurrency test to demonstrate a complete CSP flow

* Fix clang-format issues

* Fixed "Out" parameter name

* Fixing merge conflict in framework.py

* Add channel ops to framework.py no_kernel_op_set

* Seperating channel_send and channel_recv operators

* Documenting capacity type

* Update concurrency test to create go block as child block of main program

* Changing set status implementation

* add async sgd document

* fix ci

* update by comment

* update doc

* fix ssd problems

* fix box decoder op

* fix dimension problem in detection tests

* update detection doc

* Update detection doc

* Update detection doc

* update detection doc

* update detection doc

* Register more data type for reshape operator.

* Enable the SSD loss to support normalization by the total number of output locations.

* Fix the doc format.

When the second argument contains batch dimension, the axis should be 0.

Also makes elementwise ops more tolerant at handling tensors with trailing
singular dimensions.

* merge fluid dist tests

* update cmake

* Fix dist demo error

* revert trainer_id

* Enhance bipartite_match_op to support argmax matching after bipartite matching.

* Fix typo error.

Fix #8079 and remove the redundant code