[llvm] [GlobalISel] Add `G_EXTRACT_VECTOR_ELT` for `computeKnownBits` (PR #164825)

[Moritz Zielke via llvm-commits]

mooori wrote:

I've addressed the review comments and merged latest `main`. In the meantime there have also been some other changes to the `CHECK`s in `sdiv.i64.ll`.

Could the CI workflows be run again? I don't have permission to approve them.


https://github.com/llvm/llvm-project/pull/164825