Add Replicate demo and API

[chenxwh]

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Hi @zRzRzRzRzRzRzR,

This pull request makes it possible to run CogVLM2 on Replicate (https://replicate.com/chenxwh/CogVLM2, https://replicate.com/chenxwh/CogVLM2-video). I have followed your suggestions on CogVideo to organise the files and readme. Also we'd like to transfer the demo pages to THUDM so you can make modifications easily, and happy to help maintain/integrate the upcoming changes and improving the demo :)