[llvm-branch-commits] [CIR][NFC] Add scaffolding for the CIR dialect and CIROps.td (PR #86080)

[Nathan Lanza via llvm-branch-commits]

https://github.com/lanza created https://github.com/llvm/llvm-project/pull/86080

This adds no real content, it just incrementally adds some scaffolding
necessary to enable a future patch to just add our first few ops.