* Convert split, pad and pad3d kernels

* Convert slice+grad oneDNN fluid kernels to PHI

* change out->mutable_data to dev_ctx.Alloc

* gaussian random

* mkldnn to onednn renaming

* fix merge conflicts

* remove fluid code

* onednn renaming

* Move classes from mkldnn_reuse.h to onednn_reuse.h

* Migrate pool+grad, clip+grad and cast oneDNN kernels to PHI

* Refactor grad kernels into separate files

* Fix CI failures

* Fix Codestyle

* Implement reviewer suggestions

* Add new lines after includes for readability
Co-authored-by: NSilv3S <slawomir.siwek@intel.com>

* gaussian random

* mkldnn to onednn renaming

* fix merge conflicts

* remove fluid code

* onednn renaming

* Move classes from mkldnn_reuse.h to onednn_reuse.h

* Move more functions from mkldnn_helper.h to onednn_helpper.h

* Change MKLDNN to OneDNN in VLOG message
Co-authored-by: NSilv3S <slawomir.siwek@intel.com>

* gaussian random

* mkldnn to onednn renaming

* fix merge conflicts

* remove fluid code

* onednn renaming

* change header path

* change fluid import to phi

* abs relu6 fwd

* abs bwd

* gaussian_random_kernel and mkldnn-onednn renaming

* scale kernel

* whitespace

* whitespace

* revert scale migration

* whitespaces

* revert changes to gaussian kernel

* whitespaces

* remove fluid kernel and activate phi kernel

* fix parameter error

* transfer mkldnn part

* modify header file path

* fix compile error

* transfer special case

* fix lod setting and special case for layout setting

* add testcase and refine code

* move mkldnn activation kernel

* fix compile bugs

* fix compile bugs

* deal with conflict

* fix compile bugs

* fix windows compile bugs

* mkldnn unittest fix

* change mutable to alloc

* fix unittest bugs

* modify code according comment