[llvm] [WIP][TTI] Replace getStridedMemoryOpCost with getIntrinsicInstrCost (PR #165532)

[Shih-Po Hung via llvm-commits]

arcbbb wrote:

This approach doesn’t work for getGatherScatterOpCost: ARMTTIImpl::getGatherScatterOpCost walks the use chain of a provided LoadInst/StoreInst, whereas ICA currently expects an IntrinsicInst. Consider introducing getMemIntrinsicInstrCost  to cover this scenario..

https://github.com/llvm/llvm-project/pull/165532