[reland] make ShardedTensor be a Tensor and nn.Parameter (#82089)
This is the reland PR of https://github.com/pytorch/pytorch/pull/79825,
which was reverted due to multi-gpu ci failures. Fixes those failures
and reland it again.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/82089
Approved by: https://github.com/fduwjj
