Changes to make val-tagged work

[epureanudiana]

I made some adjustments to val.py and put them in a new script, val-tagged.py
I needed some adjustments in metrics.py and created a new metrics-tagged.py

The downside is that the 2 classes are almost the same
The upside is that if yolov5 changes, i think it’s easier to just sync

[epureanudiana]

you left me a comment last week:
I didn’t really check it yet but I was thinking. In metrics-tagged and val-tagged. Cannot we import from the other files everything that it’s in common and in the new files add only what it’s different?

I made this change in metrics-tagged, good idea! In val-tagged it does not make sense because the file is essentially a huge run() method which I am changing here and there.