Refactor finders into classes, add wrapper script

[jmelot]

Closes #24

@jspeed-meyers this isn't quite done, but before propagating these changes to the github sponsors scraper I wanted to check in about how you felt about the direction this is going. I added some (hopefully not too confusing/onerous) structure to the finders so they would have a consistent interface that could be called by the wrapper script.

[github-actions[bot]]

No need for rebasing :+1: behind_count is 0 ahead_count is 6

[github-actions[bot]]

☂️ Python Coverage

current status: ✅

Overall Coverage

Lines	Covered	Coverage	Threshold	Status
342	230	67%	0%	🟢

New Files

File	Coverage	Status
funderfinder/sources/init.py	100%	🟢
funderfinder/sources/_finder.py	86%	🟢
funderfinder/utils/init.py	100%	🟢
tests/sources/test__finder.py	83%	🟢
tests/sources/test_github_sponsors.py	92%	🟢
TOTAL	92%	🟢

Modified Files

File	Coverage	Status
funderfinder/sources/github_sponsors.py	55%	🟢
funderfinder/sources/numfocus.py	69%	🟢
tests/sources/test_numfocus.py	100%	🟢
TOTAL	75%	🟢

updated for commit: 3e9773d by action🐍

[jmelot]

@jspeed-meyers Thanks for your earlier comments, I think I addressed them. For the sake of completeness, I propagated these changes to the github sponsors as well (I hope you don't mind!). Can you please take a look and let me know if you are ok with what I did there (sorry the diff is so painful to look at because of the indentation change - basically I added a run method that follows what is done in the other scrapers, and also moved a bit of parsing functionality out into the base class)? If so I think we can merge this!

[jspeed-meyers]

LGTM. Merging!