Add a new FTAG test/example and specify defaults for flavor tagging tools

This adds a new minimal example showing how to use the flavor tagging tools in analysis. Quite a few frameworks have incorrect implementations unfortunately.

We've also added a series of default values since there is only one recommended way for most analyses to use flavor tagging: there are a lot of options but most users won't need to change any of them.

Highly inspired from @dguest's MR !75921 (closed) but fixing some remaining issues