Add cases to `output` tests to cover license summary

It turns out we're not covering logic in the `output` package related to the `LicenseSummary` field - we should expand our test fixtures for that package to include those cases.

I think we need at least two new sets of tests related to license summarizing since you can have `ShowViolations` either true or false - it might be possible though to reuse some of the existing test cases with a field or two changed, so we might want to introduce a new function(s) that return the test cases and accept some parameters