Support huggingface mirror

[undefine-man]

In my country, huggingface and github(sometimes) can not be access directly. There are two ways to use huggingface, one is use proxy, second is use huggingface mirror. Docker is the first choose to deploy app, but setting proxy is not so the best choose to access huggingface, because proxy not only cost fee also slow for some website. So mirror is the best choose, it is ultra fast and no need fee.

So hope LocalAI can support mirror like other docker app. Some app set environment variables when deploying container to simply support mirror like
HF = https://hf-mirror.com/
GH = https://ghproxy.it/
or
HF = hf-mirror.com
GH = ghproxy.it