[Feature request] Allow batch tagging

Hello, thank you for making standalone tagger.

For 3090 GPU, GPU utilization is only about 30% when processing a directory. I think using a batch of 4-8 would significantly improve performance.

[corkborg]

Hi!

In this project, we are using a model converted to the onnx format.

To perform batch execution with onnx, it seems necessary to support batch execution when converting the model.

It seems quite difficult to support batches at the moment.

I hope there is a better way.

microsoft/onnxruntime#9867