Add nightly build workflow (#2363)

Summary:
Onboard ExecuTorch to Nova wheel build workflow https://github.com/pytorch/test-infra/wiki/Using-Nova-Reusable-Build-Workflows.  The wheel is built using `python setup.py bdist_wheel`.  All the pre-build, post-build, and smoke test scripts are placeholders.

Having this will enable the team to easily add more logic into the build scripts later.

### Testing

* Linux wheel build https://github.com/pytorch/executorch/actions/runs/8243162791
* macOS wheel build https://github.com/pytorch/executorch/actions/runs/8243162792

Pull Request resolved: https://github.com/pytorch/executorch/pull/2363

Reviewed By: guangy10

Differential Revision: D54788737

Pulled By: huydhn

fbshipit-source-id: 3b1daf8cc6949f5229cd73eedd8db26066669dfc