//   %0 = tf.Pack(%input) {axis = 0} // %input : tensor<2x3xf32>
//
// can be canonicalized to
//
//   %shape = "tf.Const"() {value = dense<[1, 2, 3]> : tensor<3xi64>}
//   %0 = tf.Reshape(%input, %shape)
struct ConvertPackToReshape : public OpRewritePattern<PackOp> {
  using OpRewritePattern<PackOp>::OpRewritePattern;

  LogicalResult matchAndRewrite(PackOp pack_op,
                                PatternRewriter &rewriter) const override {