a0d449016b
The LLVM dialect no longer has its own vector types. It uses `mlir::VectorType` everywhere. Remove `LLVM::getVectorElementType` and use `cast<VectorType>(ty).getElementType()` instead. This commit addresses a [comment](https://github.com/llvm/llvm-project/pull/133286#discussion_r2022192500) on the PR that deleted the LLVM vector types. Also improve vector type constraints by specifying the `mlir::VectorType` C++ class, so that explicit casts to `VectorType` can be avoided in some places.