Full SDXL DreamBooth finetuning, LoRA extraction

In the dreambooth community, it has been empirically shown that extracting a LoRA results in better performance than directly training a LoRA. Enabling a full dreambooth finetune of SDXL would not only enable this functionality, but also further enable users to extract and test out LoRAs of multiple different network ranks without having to rerun the training script multiple times.