[llvm] workflows/build-ci-container: Add an arm64 container (PR #120828)

[Tom Stellard via llvm-commits]

tstellar wrote:

@boomanaiden154 I've rebased this on main.  Can you take another look, since I had to make some non-trivial changes.   I've tested this here: https://github.com/tstellar/llvm-project/actions/runs/13065064067/job/36455960691

https://github.com/llvm/llvm-project/pull/120828