[shardformer] support inplace sharding

[ver217]

Motivation

Current sharding method is

1. Create a new parameter
2. Shard the new parameter
3. Shard the old parameter
4. Copy the old parameter shard to new one

This has below shortcomings:

1. Not memory efficient
2. Must handle tied weights again (after sharding)
3. Need to update param groups of optimizer (if using lazy init and sharding after optimizer init)

Method

Thus, I think we can shard parameters inplace. This is memory efficient and we don't need to handle tied weights or param groups again.

[ver217]

Completed in #4251