Read SpinQuant checkpoints (#5259)

Summary:
Pull Request resolved: https://github.com/pytorch/executorch/pull/5259

Read SpinQuant checkpoints that is in exported with scales/weights.

bypass-github-export-checks
bypass-github-pytorch-ci-checks
bypass-github-executorch-ci-checks

Reviewed By: iseeyuan, helunwencser

Differential Revision: D62403094

fbshipit-source-id: 283ae18a1d2053306677086b9edd5cb5f38120ee