* add coalesce_tensor kernel

* polist coalesce_tensor kernel

* add sig and InferMeta

* add testcase

* add legacy_api.yaml

* fix infermeta

* fix yaml

* fix kernel implementation

* add compile dependency of phi/kernels

* fix MetaConfig

* add python api

* add and fix testcase

* rnn.py add import

* change _C_ops.coalesce_tensor

* remove useless comments

* add SetBackend

* restore XPU kernel temporarily

* fix code according to PR comments