[Feature] Low priority: Allow specifying HuggingFace model/repo name in `lmdeploy convert`

### Motivation

This is **not** an important feature, but I figured I'd mention it because it was a small point of friction that I think could be improved in the future. Currently my script does this:
```
pip install 'huggingface_hub[cli,hf_transfer]==0.23.2'
export HF_HUB_ENABLE_HF_TRANSFER=1
huggingface-cli download lmdeploy/llama2-chat-70b-4bit --local-dir /root/llama2-chat-70b-4bit
lmdeploy convert llama2 /root/llama2-chat-70b-4bit --model-format awq --group-size 128 --tp $(nvidia-smi -L | wc -l) --dst-path /root/turbomind-model-files
```
Ideally I could just write this:
```
lmdeploy convert llama2 lmdeploy/llama2-chat-70b-4bit --model-format awq --group-size 128 --tp $(nvidia-smi -L | wc -l) --dst-path /root/turbomind-model-files
```
And it as a bonus nice-to-have it would be cool if I only needed enough disk space to fit one version of the model - e.g. for 70B 4bit model, if my disk space was 40GB, ideally that would be enough. But currently ~80GB is required because both AWQ and turbomind formats must be stored on disk at the same time until turbomind conversion is complete. But this feature is not very important because disk space is cheap.

### Related resources

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### Additional context

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