Quest: Add Quad2 and Relu2 Softmax Variations

[gkielian]

Just heard about these, would be interesting to have these in the comparison matrix:

https://openaccess.thecvf.com/content/ICCV2023/papers/Zhang_SAL-ViT_Towards_Latency_Efficient_Private_Inference_on_ViT_using_Selective_ICCV_2023_paper.pdf

See Contributing_Features.md for a guide for how to add these in.

Quest Steps:

1. Add Variations to the softmax_variations.py
2. Import Variations to the model.py, and add to if-else blocks
3. Add to train.py
4. Create a explorations/softmax_variations.json
5. Create PR