[mlir] Fix Windows build

[nicolasvasilache]

Summary

MSVC does not seem to like certain forward declarations.

https://reviews.llvm.org/D80728 introduces an error where
seemingly unrelated .cpp files that include the .h
(but do not otherwise use the class that depends on the forward declaration).

Instead of forward declaration, include the full vector ops definition.

mlir/include/mlir/Dialect/Linalg/Transforms/Transforms.h

 //===- Transforms.h - Linalg transformations as patterns --------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef DIALECT_LINALG_TRANSFORMS_TRANSFORMS_H_
 #define DIALECT_LINALG_TRANSFORMS_TRANSFORMS_H_
 
 #include "mlir/Dialect/Linalg/Utils/Utils.h"
+#include "mlir/Dialect/Vector/VectorOps.h"
 #include "mlir/IR/PatternMatch.h"
 #include "llvm/ADT/SmallBitVector.h"
 
 namespace mlir {
-namespace vector {
-
-class TransferReadOp;
-class TransferWriteOp;
-
-} // namespace vector
-
 namespace linalg {
 
 struct LinalgTilingOptions;
 
 //===----------------------------------------------------------------------===//
 // Transformations exposed as function calls.
 //===----------------------------------------------------------------------===//
 using LinalgLoops = SmallVector<Operation *, 4>;