[llvm] [llc] Register pass plugin callbacks with the new pass manager (PR #217727)

[Xaver Fabian via llvm-commits]

XFabian wrote:

Yes, you are right. It does not have to be a machine pass. I added a test file that uses the existing `goodbye` function pass to check that it reaches the pipeline


https://github.com/llvm/llvm-project/pull/217727