Download counter: Also count downloads via Packagist API

What kind of feature do you want?

TER's download counter could also integrate the downloads via Packagist. These are available for each released version via the packagist API, e.g.

https://packagist.org/packages/webdevops/metaseo/downloads.json

What are the benefits?

Now that we see more downloads via Packagist than via TER (with or without composer), I think it just makes sense to get a true picture by counting Packagist downloads as well. Speaking for myself, it makes a difference in terms of motivation to continue development when I can see that the software I'm writig also is used by the community.

For metaseo 3.0.0, there's currently 445 downloads via Packagist and 295 downloads via TER whereas MetaSEO's documentation strongly recommends to go for the TER repos (via composer or via EM).

This feature implies, that TER knows Packagist's package name for an extension. Multiple API URLs should be possible for the case the package name changes over time (e. g. MetaSEO has changed its name in the past).