Llm-embed-onnx

- Initial release. This plugin provides seven embedding models:`onnx-bge-micro`, `onnx-gte-tiny`, `onnx-minilm-l6`, `onnx-minilm-l12`, `onnx-bge-small`, `onnx-bge-base`, `onnx-bge-large`. [1](https://github.com/simonw/llm-embed-onnx/issues/1)