Often, when doing major changes to the generated projects, we need to manually update a lot of files. It would be convenient to have a way to automatically update the content of all generated files, so we can inspect them via git diff or during PR and see if there's anything suspicious.

I think this should be implemented as an option to our test-suite stanza, because when you have multiple executables, cabal installs all of them, and we don't want our golden-generators to be installed on user machines near the summoner executable itself.