[llvm] [Offload] Add MPI Proxy Plugin (PR #114574)

[Joseph Huber via llvm-commits]

https://github.com/jhuber6 commented:

This is obviously a huge patch, I don't know what would be required to run a bot on this. Maybe @jplehr can chime in.

https://github.com/llvm/llvm-project/pull/114574