[vmap] symintify : is_same_size and split_with_sizes (#111491)
Partial : https://github.com/pytorch/pytorch/issues/111312
Reference: Point 1 of https://github.com/pytorch/pytorch/issues/111312#issuecomment-1769079147
Should this have a test?
Pull Request resolved: https://github.com/pytorch/pytorch/pull/111491
Approved by: https://github.com/Skylion007, https://github.com/zou3519
