* comm_context and static init

* refactor: move to phi/core/distributed

* refactor: avoid mutable_data usage

* fix: windows sock

* fix: device without nccl
Co-authored-by: Wen Sun <syl1887415157@126.com>

* refactor: use base class

* fix: incorrect deps

* fix: add missing header

* refactor: update class structures

* fix: bkcl typo

* fix: remove redundant def

Note: this is a temporary solution, should be replaced once reduce kernel
is natively supported on KL2

* refactor: simplify send, recv interfaces

* refactor: rm send_partial, recv_partial, all_gather_partial

* XPU support eager mode

* add unittest for XPU eager mode

* minor bugfix

* minor bugfix, test=kunlun

* correct copyright info

* 1. remove unsed vars/funcs
2. ProcessGroupBKCL inherit from ProcessGroupStream

* bugfix for fp16 in eager mode multi-card, test=kunlun

* rebase & fix a few issues

* use new processgroup interface, test=kunlun

* fix compile issue, test=kunlun