TrkGlobalChi2Fitter: Cleanup of the GlobalChi2Fitter code

I accidentally broke the previous iteration of this merge request (!22618 (closed)) to the point where it would be more elegant to re-open it with a clean slate.

It's a bit of a large merge request, but it's not as scary as it looks. Most of the changes are in f4c7d23e which should be purely syntactical; it contains a manual effort to make every single file in the GlobalChi2Fitter code base properly formatted and readable. For the rest, this merge request removes a largely redundant class (made redundant by a several past changes to how the fitter works), removes a bunch of redundant data members and updates the code to use the new macro-based logging and status code checking system.