[Support Requests] Add Conditional dropout

[Curlypla]

Conditional dropout means the prompt or caption on the training image is dropped, and the caption is "blank". The theory is this can help with unconditional guidance, per the original paper and authors of Latent Diffusion and Stable Diffusion.

so just set a parameter like 0.1 that will, for example, do it 10 times every 100 frames

+It's really easy to add