support Super Mario merge(DARE)

[wkpark]

Combine any two models using a Super Mario merge(DARE)

mask_rate fixed to 0.5. (p = 0.5)

• https://github.com/wkpark/sd-webui-model-mixer/discussions/120 by @CCpt5
• https://github.com/martyn/safetensors-merge-supermario/blob/main/merge.py#L9C1-L19C
• https://github.com/yule-BUAA/MergeLM/blob/main/model_merging_methods/mask_weights_utils.py#L20