[llvm] [mlir] [IR] Split Br into UncondBr and CondBr (PR #184027)

[Alexis Engelke via llvm-commits]

aengelke wrote:

@arsenm I don't think so, given that the bitcode doesn't change at all. This change purely affects the in-memory representation.

https://github.com/llvm/llvm-project/pull/184027