feat: support process group

[wangraying]

BREAKING CHANGE:

• model.with_bagua(...) now can specify process groups

[todo]

remove the dependency on torch process group

bagua/bagua/torch_api/communication.py

Lines 313 to 318 in be66fbc

	# TODO remove the dependency on torch process group
	if not dist.is_initialized():
	torch.distributed.init_process_group(
	backend="nccl",
	store=_default_store,
	rank=get_rank(),

---

This comment was generated by todo based on a TODO comment in be66fbc in #228. cc @BaguaSys.

[todo]

combine **inplace API

bagua/bagua/torch_api/communication.py

Lines 949 to 954 in bc126fe

	# TODO combine **inplace API
	def alltoall_inplace(
	tensor: torch.Tensor,
	comm=None,
	):
	"""The in-place version of :func:`alltoall`."""

---

This comment was generated by todo based on a TODO comment in bc126fe in #228. cc @BaguaSys.

[NOBLES5E]

see comments

[github-actions]

[blackfmt] _{reported by reviewdog 🐶}

Suggested change

	@unittest.skip("fixme")
	# @skip_if_cuda_not_available()
	@unittest.skip("fixme")
	# @skip_if_cuda_not_available()

[github-actions]

[blackfmt] _{reported by reviewdog 🐶}

Suggested change

	# @skip_if_cuda_not_available()
	# @skip_if_cuda_not_available()