Implement `torch._foreach_lerp` (#87562)
As per title.
- [ ] ~~Q: Do we want `torch._foreach_lerp.ScalarList` as well?~~
- [ ] ~~we might want to have `ATen/native/cuda/lerp.cuh` and include it in `ATen/native/cuda/Lerp.cu` and `ATen/native/cuda/ForeachTernaryOp.cu`~~
Related:
- https://github.com/pytorch/pytorch/issues/58833
- https://github.com/pytorch/pytorch/issues/71683
Pull Request resolved: https://github.com/pytorch/pytorch/pull/87562
Approved by: https://github.com/ngimel
