[dtensor] support creating DTensor in submesh (#95458)
This PR supports creating DTensor in a submesh, if the rank is not
participating in the mesh, we assign the local tensor to be empty
tensor, and do nothing in the operator dispatch
Differential Revision: [D43643577](https://our.internmc.facebook.com/intern/diff/D43643577)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/95458
Approved by: https://github.com/XilunWu
