good first issuetf
Description
The current GaussianMLPModel actually represents several architecture variants, which makes it difficult to use and to test. We should split it into several variants based on architecture (and possibly parameterization)
| description | mean | std_param |
|---|---|---|
| fixed variance | MLP1 | parameter (trainable or not) |
| split network | MLP1 | MLP2 |
| shared network/multi-headed | MLP1/head1 | MLP1/head2 |