New source and more: apk.support

Well, yeah I see there's already support for Apkpure, then why yet another 3rd party store? because it's even better. Its library is much larger since it can scrap from Google Play on demand, while most other alternative stores only upload apk files for selective apps. I guess the coverage is even broader than Google Play since some old apps currently not in Google Play can be found there, too.

I found two projects relating to deal with this site, [vijaykumar234/apk-support-downloader](https://github.com/vijaykumar234/apk-support-downloader) and [shauryashekhar/webScrapper](https://github.com/shauryashekhar/webScrapper), although I didn't test them myself and dunno if they still work.

Further more, the webScrapper project covers quite a lot of sites and maybe requests like #341 and #552 are easily doable now.

Start by reviewing Obtainium's existing APKPure support and the two linked projects, apk-support-downloader and webScrapper, to determine whether apk.support can be integrated. Check the related requests #341 and #552 for context; done should mean adding a working apk.support source with the expected app coverage and update behavior.

Written by the indexing model from the issue text.