* open header for custom kernel

* add core utils

* tidy core code

* tify header

* tidy include

* tidy namespace

* resolve conflit

* fix unittest and coverage

* remove platform using

* resolve conflict

* resolve conflict

* fix digamma namespace error

* fix xpu full kernel error

* fix xpu full kernel error

* polish details

* add place for lib storage

* Migrate Dim and DDim from paddle::framework into pten namespace

* fix paddle::framework::Array

* fix framework::Array

* polish some error message in framework, test=develop

* fix unittest error, test=develop

* replace PADDLE_ENFORCE, test=develop

* polish details based review comment, test=develop

Add examples for error message writing specification - NotFound, OutOfRange, AlreadyExists, PermissionDenied (#21134)

* add examples for error msg spec, test=develop

* change ENFORCE to ENFORCE_**, test=develop

* add more already exists examples, test=develop

test=develop

test=develop