Switch member calls to isa/dyn_cast/cast/... to free function calls. (#89356)

This change cleans up call sites. Next step is to mark the member
functions deprecated.

See https://mlir.llvm.org/deprecation and
https://discourse.llvm.org/t/preferred-casting-style-going-forward.

mlir/lib/Conversion/VectorToLLVM/ConvertVectorToLLVM.cpp

@@ -631,8 +631,7 @@ static Value createMaskNeutralValue(ConversionPatternRewriter &rewriter,
                                     Type vectorType) {
   const auto &floatSemantics = cast<FloatType>(llvmType).getFloatSemantics();
   auto value = getMaskNeutralValue(MaskNeutral{}, floatSemantics);
-  auto denseValue =
-      DenseElementsAttr::get(vectorType.cast<ShapedType>(), value);
+  auto denseValue = DenseElementsAttr::get(cast<ShapedType>(vectorType), value);
   return rewriter.create<LLVM::ConstantOp>(loc, vectorType, denseValue);
 }