Utility for calculating fisher expectation

[EthanMarx]

Write a utility for automatically calculating expectation of posterior uncertainties from a Fisher analysis. See A.2 in https://arxiv.org/pdf/1511.08752.pdf

[saleem-muhammed]

In case it is useful, there is a package known as gwbench for computing uncertainties using Fisher formalism. Here is the methods paper

[mcoughlin]

Also Jan Harms maintains gwfish: https://arxiv.org/abs/2205.02499