[llvm] [Github][Bazel] Add Workflow to Run Bazel Build (PR #165071)

[Aaron Siddhartha Mondal via llvm-commits]

https://github.com/aaronmondal commented:

I like that this reduces reliance on buildkite, though I'm fairly biased as I have strong interest in this as well.

@jaroeichler and I are generally looking to sponsor infra for bazel workflows in LLVM as well. We've just recently started to build out infra, so I can't give a too exact timeframe for that (maybe around 1-3 months?) But regarding runner images we might be able to contribute to this effort sooner. (Jaro, WDYT?)

https://github.com/llvm/llvm-project/pull/165071