[Feat] Model Structure Update API

[YuanmingLeee]

Software and Hardware Versions

ModelCI v1.x.x, CUDA Version vx.x.x, GPU device used...

Problem description

Request a new feature to modify the model structures. For example, add a layer, remove a layer or adjust a layer.

Expected Behavior

The model is updated, ensured the update is valid, and saved into the database.

[HuaizhengZhang]

Please create an experimental dir in the fine-tuner rather than put it in the root of modelci dir. This organization is more logical. In doing so, we can track your code more easily.

If I want to add a new function, I can test it first in my function/experimental dir.