Implement LAVA method

Implement Just, Hoang Anh, Feiyang Kang, Jiachen T. Wang, Yi Zeng, Myeongseob Ko, Ming Jin, and Ruoxi Jia. [Lava: Data valuation without pre-specified learning algorithms.](https://arxiv.org/abs/2305.00054) arXiv preprint arXiv:2305.00054 (2023).

The paper's code can be found in [this repository](https://github.com/ruoxi-jia-group/LAVA).

To compute Optimal Transport we can use either [POT](https://pythonot.github.io/) and/or [GeomLoss](https://www.kernel-operations.io/geomloss/). The latter is Pytorch specific whereas the former isn't.