[llvm] [VectorCombine] Add Ext and Trunc support in foldBitOpOfCastConstant (PR #157822)

[Hongyu Chen via llvm-commits]

XChy wrote:

@Rajveer100. Do you mean replacing terms like `<i32 1, i32 2, i32 3, i32 4>` with `splat (i32 1)` in the original testcases?

https://github.com/llvm/llvm-project/pull/157822