对标算子

本OP对标torch库中的matmul算子，功能略有不同。部分对标的功能参考torch.matmul文档中的示例：

# batched matrix x batched matrix
tensor1 = torch.randn(10, 3, 4)
tensor2 = torch.randn(10, 4, 5)
torch.matmul(tensor1, tensor2).size() # torch.Size([10, 3, 5])
# batched matrix x broadcasted matrix
tensor1 = torch.randn(10, 3, 4)
tensor2 = torch.randn(4, 5)
torch.matmul(tensor1, tensor2).size() # torch.Size([10, 3, 5])