Support PyTorch main commits & vLLM PRs

[BoyuanFeng]

Currently the CI supports PyTorch stable (2.7.1) and pulls latest docker image from vLLM.

Feature requests:

• Support PyTorch main commit. So we can track regression due to PyTorch side.
• Support vLLM commits from forker repo or PR. vLLM github repo requires contributors to fork the repo and create a PR. It does not allow creating a branch in vLLM github repo.