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/Dialect/SparseTensor/IR/SparseTensorDialect.cpp

@@ -2078,7 +2078,7 @@ struct SparseTensorAsmDialectInterface : public OpAsmDialectInterface {
   using OpAsmDialectInterface::OpAsmDialectInterface;
 
   AliasResult getAlias(Attribute attr, raw_ostream &os) const override {
-    if (attr.isa<SparseTensorEncodingAttr>()) {
+    if (isa<SparseTensorEncodingAttr>(attr)) {
       os << "sparse";
       return AliasResult::OverridableAlias;
     }