make logging less verbose

[hturki]

Thanks for the great work! Here are some minor proposed changes to make the logging a bit less verbose (that I could desirable when using dust3r inside of larger offline training pipelines). I also tweaked compute_global_alignment so that it doesn't use autocast (within which it seems to currently fail) and actually returns the global alignment loss.

As a feature request, it would be nice if dust3r could be packaged as something installable via pip (ie: either pip install duster or pip install git+https://github.com/naver/dust3r.git)