Implement differentiable coverage probability regularizer

[macio232]

Description

The method described in Calibrating Neural Simulation-Based Inference with Differentiable Coverage Probability paper.

Implementation

New loss class in the inference module, similar to the NRELoss ->BNRELoss enhancement.

Two separate classes, one for NRE, and one for NPE.

Alternatives

I did not consider alternatives.

[francois-rozet]

Hello @macio232 thanks for the feature request! I'll take a look at the PR soon!