[llvm] [libc++] Add Docker images to support incoming pre-merge CI transition (PR #144597)

[Aiden Grossman via llvm-commits]

https://github.com/boomanaiden154 commented:

This seems like a duplicate of what we have to put in the runner values YAML file that we have to have in llvm-zorg/premerge?

eg https://github.com/llvm/llvm-zorg/blob/main/premerge/linux_runners_values.yaml

https://github.com/llvm/llvm-project/pull/144597