Provide the afterReporting() hook with all the language reports

[harriha]

For post-processing purposes via the afterReporting() hook it would be useful to have all the language reports there.

It looks like this would be fairly straight-forward to implement and would not cause backwards compat issues as currently the function does not take any arguments. My suggestion for the function signature would be afterReporting(reports: object[]), where each item in the array is the resulting langResults object as-is.

I can look into providing a PR for this if you'd be willing to merge this change.