Add cached conda env files for macos (arm64, x86) (#87541)
So far, we only cache macos conda dependency for build workflow. All the test dependencies are still not cached and installed by the CI. This PR introduces a new `.github/requirements` directory which I plan to explicitly include all the conda and pip build and test dependencies across all platforms. This allows pip and conda installation to be consolidated in one place (and properly cached)
Those conda dependencies come from https://github.com/pytorch/pytorch/blob/master/.jenkins/pytorch/macos-common.sh. Once this PR is merged, I will follow up with another one to clean up all conda installation from that file (to make sure that nothing break along the way)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/87541
Approved by: https://github.com/ZainRizvi
