[llvm] [IR] Implementation and lowering of bitinsert and bitextract (PR #200605)

[Pedro Lobo via llvm-commits]

pedroclobo wrote:

I've removed some tests which produced `poison` and trimmed some of the codegen tests cases while maintaining representative coverage for the 6 architectures. This removed ~5510 lines of redundant tests.

https://github.com/llvm/llvm-project/pull/200605