[clang] [clang][CodeGen] Convert between `bfloat` and `half` through `float` (PR #233391)

[Akash Manna via cfe-commits]

akash-manna-sky wrote:

I hadn't seen that RFC before, now read that. Nothing implements it yet though. The expansion here is the same one the RFC describes, and `EmitFloatingCast` is the only spot that would need to change to a direct `fptrunc/fpconvert` later. Fine to land this as the interim fix, or do you want to wait for the IR change? What is your thought here? 


https://github.com/llvm/llvm-project/pull/233391