Validation implementing

[seniorsolt]

Simple validation logic was implemented

ValidationBaseDataLoader class is added. This class is primarily a clone of StableDiffusionBaseDataLoader with an added boolean variable validation in the create_dataset method.

To process new variable and divide train and validation datasets DataLoaderMgdsMixin was modified. UI was updated to provide radio buttons for validation logic.

It's hard to consider that PR ready to merge. I suggest we discuss this further to ensure alignment with your future plans.

[mx]

I don't follow why this requires duplicating the entire data loader class.

[seniorsolt]

This solution was cobbled together on the fly. This class can be inherited from any other, with an overloaded create_dataset method. Also there are other ways: modifying every data loader class and monkey patching.

If you have a better suggestion, welcome.