[PyTorch][ExportedProgram] add 'is_lifted_tensor_constant' and 'get_lifted_tensor_constant' utils (#120546)
as title
Differential Revision: [D54149274](https://our.internmc.facebook.com/intern/diff/D54149274/)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/120546
Approved by: https://github.com/kirklandsign
