[llvm] [DAG] Peek through bitcasts when canonicalizing constants to the RHS on commutable instructions (PR #112682)

[Simon Pilgrim via llvm-commits]

RKSimon wrote:

closing this in preference for #112710 (the FoldConstantArithmetic cleanup is just as valid for that PR btw)

https://github.com/llvm/llvm-project/pull/112682