PyTorch Nightly support in Dockerfile

[sbhavani]

In https://github.com/NVIDIA/TensorRT-LLM/blob/main/docker/common/install_pytorch.sh, we support the latest PyT stable version (e.g. 2.5.1) that corresponds with NGC version (e.g. 24.11). However, the stable version lags behind the w.r.t. to CUDA, cuDNN, NCCL, etc.

It would be helpful to also support the PyT nightly wheel that corresponds with the NGC release which would include more bug fixes and features.