Nightly build for for iOS (#26074)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/26074
### Summary
This PR creates a nightly job for iOS builds. The job will generate a couple of static libraries that contains three architectures(x86, arm64, armv7s) and upload them to AWS s3.
### Note
The test phase in this job is missing right now, meaning if there is a linking error, we won't be able to know it. To add the test jobs, we have to put a dummy test App in the repo and manually link the libraries to the app after the build finishes. This will be done in the next following PRs
Test Plan: Imported from OSS
Differential Revision: D17363066
Pulled By: xta0
fbshipit-source-id: 5beeb4263af5722f0a852297023f37aaea9ba4b1
