[llvm] [CostModel] Add type-based cost model for get.active.lane.mask intrinsic (PR #130132)

[Paul Walker via llvm-commits]

https://github.com/paulwalker-arm approved this pull request.

I agree with @rj-jesus's `FMF` suggestion but otherwise this PR looks good to me.

https://github.com/llvm/llvm-project/pull/130132