Implement more Dims distributions

Description

We have these currently:

• Scalar
• Vector

We should implement most of the existing distributions. Univariate should be straightforward.

Multivariate may be trickier. We would likely want to reuse the regular methods like we do for ZeroSumNormal and MvNormal, but we need to test carefully.

Distribution factories like Mixture, Truncated, Censored will be the trickiest. The first step is to implement an extend_dist_dims function (to recreate the input distributions with more dims, just like we used to having to change_dist_size before).