Allow multiple log message types (besides ErrorMessage)

[Nutzzz]

Example shown in PR #78

[Nutzzz]

From newest CHANGELOG:

Finally, I've been thinking a lot about result types. Over the years, I've updated GameFinder to use various different approaches for dealing with errors. This update is the beginning of me phasing out my hacky OneOf<TResult, ErrorMessage> solution, and replacing it with FluentResults.

...So it looks like you're working on it. PR #78 closed.