[Feature] Support rewritting the origin model in mmrazor

[HIT-cwh]

The interface in mmrazor to get the observed model has to be changed from post_process_for_mmdeploy to get_deploy_model.

[CLAassistant]

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2 out of 3 committers have signed the CLA.

✅ pppppM
✅ HIT-cwh
❌ liukai

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