integration with gomega

Would love to have this so can have more expressive steps that don't need to reinvent the error logic.

https://github.com/onsi/gomega

I'm happy to work on this if you can give any pointers on where to start

Start by reviewing godog's existing step and error handling, then read the linked Gomega project to identify a suitable integration boundary. Define the supported expressive-step behavior and verify it with integration tests before considering the issue done.

Written by the indexing model from the issue text.