[llvm] AMDGPU/GlobalISelDivergenceLowering: select divergent i1 phis (PR #78482)

[Petar Avramovic via llvm-commits]

petar-avramovic wrote:

Had to hide copies between S1-register-with-reg-class and register-with-reg-class-no-LLT from expensive checks buildbots (they run machine verifier). This is required between patches 3 and 4, patch 4 fixes this.
This is same as https://github.com/llvm/llvm-project/pull/76145 that was reverted.

https://github.com/llvm/llvm-project/pull/78482