* move DeviceContextPool to phi

* add EmplaceExternalContextFunc

* update namespace

* update cmake

* fix bugs and create context_pool_impl.h

* replace platform::is_xxx_place

* fix bugs

* update generator

* fix bugs

* fix bugs

* fix bugs

* fix bugs

* fix bugs

* fix bugs

* fix bugs

* fix enforce usage

* Revert "fix enforce usage"

This reverts commit 5f521f08a69713cee506e64a00ec6d9fba709e27.

* fix bugs

* rm XPUDeviceContext and CustomDeviceContext

* fix bugs

* fix fix context init bug

* fix bugs after merge

* fix bugs

* fix name

* fix mutable_data

* update and fix bugs

* fix bugs

* update

* fix bugs

* fix name

* fix bugs

* merge

* fix bugs

* create context_pool in phi/backends

* create context_pool in phi/backends

* fix bugs

* fix xpu bugs

* fix rocm bugs

* fix bugs

* fix bugs

* fix bugs

* fix xpu bugs

* update

* update

* fix bugs

* fix bugs

* move gather_scatter_kernel from fluid to phi

* mv gather_scatter_kernel to gather_scatter_functor

resort .cu headers, set clang-format not sort include block and consider .cu as main source file (#43633)

* [Phi] move put_along_axis/take_along_axis/maxout

* use phi::Copy