[llvm] [GlobalIsel] Import GEP flags (PR #93850)

[Thorsten Schütt via llvm-commits]

tschuett wrote:

`MachineInstr::copyFlagsFromInstruction` had no support for `getelementptr`. This PR adds support for copying the flags. `IRTranslator::translateGetElementPtr` blindly takes the flags from the GEP. In some cases, it already added `nuw` to the ptradd. There is no filter mechanism in `translateGetElementPtr`

https://github.com/llvm/llvm-project/pull/93850