Use NS weights for posterior plots and quantiles
If working with the outputs of nested sampling code and we have the weights stored in the
Result object we should allow the
plot_corner function to use all the nested samples, but with weights applied (as is done in dynesty and ultranest). This will reduce the sampling noise especially in the wings of the posteriors. We should also look at the dynesty quantile function, which will use the weights to work out quantiles, which again should reduce the random noise on the values.