async function matmul(a, b) {
    const op = await TensorOpRegistry.matmul;
    return await op({ a, b });
}
Matrix product of two tensors.
Inspired by https://pytorch.org/docs/stable/generated/torch.matmul.html
@param {Tensor} a the first tensor to be multiplied
@param {Tensor} b the second tensor to be multiplied
@returns {Promise<Tensor>} The matrix product of the two tensors.