Add support for inessai sampler

[mj-will]

Standard information about the request

This is a: bug fix, new feature, efficiency update, other (please describe)

This change affects: inference

This change changes: the nessai sampler to support the importance nested sampler version

This change: is tested via an example, follows style guidelines (See e.g. PEP8), has been proposed using the contribution guidelines

This change will: does not break any existing code

Motivation

With the release of nessai 0.12.0, a method for mapping from the prior to the unit hypercube is no longer required for the importance nested sampler (ins). This means we can support the ins (inessai) with a few minor changes to the existing implementation.

Contents

Updates to the existing class so that it supports the importance_nested_sampler option. This is False by default.

I also added a second class INessaiSampler that has this default switch to True and has the name set to inessai.

This means there are two ways of calling the importance nested sampler.

Testing performed

Run the example included in examples/inference/samplers/

Additional notes

To-do

• Test checkpoint after this change, since it reworks the samples property.

• Test on BBH

• The author of this pull request confirms they will adhere to the code of conduct