* Switch to mirrors.bazel.build where possible
* Switch from .zip to .tar.gz for smaller downloads (it's also the default download on UNIX)
* Use direct GitHub URLs in Bazel files for clarity
* Don't pass patches to local_repository
* Remove github_repository()
* Switch to GitHub actions/checkout@v2 which is faster
* Use faster extraction method for LLVm on Windows
* Move LLVM_VERSION_WINDOWS to the shell script since it's not a CI-specific value
* Change GITHUB_TOKEN to GITHUB
* Don't show timestamps for GitHub Actions
* Factor out some options from GitHub Actions
* Tell Bazel to stay on the same volume in GitHun Actions
* Display progress output when downloading toolchains
Co-authored-by: GitHub Web Flow <noreply@github.com>
