[iOS] Add LibTorch nightly build (#69341)
Summary:
Add LibTorch nightly build for using in LibTorchvision.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/69341
Test Plan:
CI jobs: https://fburl.com/lbyjzpxz
1. Validate lib is uploaded to link https://ossci-ios-build.s3.amazonaws.com/libtorch_ios_nightly_build.zip
2. Download lib from the link and validate `version.txt` is correct
3. Test the lib in HelloWorld demo
Imported from OSS
Reviewed By: xta0
Differential Revision: D32901836
Pulled By: hanton
fbshipit-source-id: 8622c3e6052cec2039bc15dea0d495ec1a8186cb
