Submodule extraction logic addition

[soulsharp]

This PR adds the following features -

• Add logic to extract and save submodules using torch.fx, the first layer of which is always the conv_layer whose channels needs to be pruned
• Adds a new file compress/osscar_utils.py which contains some newly added osscar-specific utilities in addition to others that were included here as par of a refactor
• Minor docstring fixes