Add Greasy Fork integration

[YDX-2147483647]

What kind of change does this PR introduce?

• [ ] Bugfix
• [x] New Feature
• [ ] Feature Improvement
• [ ] Refactoring
• [ ] Documentation
• [ ] Other, please describe:

Description:

Greasy Fork is a site for user scripts. This PR adds integration for greasy_fork_id.

Greasy Fork provides their data in a simple and straight forward greasyfork.org/scripts/*.json (e.g. https://greasyfork.org/scripts/1.json) and no token is required.

(I've been using it for a few months, and it always works.)

Checklist:

• [x] I have read the CONTRIBUTING document.
• [x] My changes don't require a change to the documentation, or if they do, I've added all required information.

[YDX-2147483647]

Sorry I have no idea why the CI fails and what build-pipeline does… I notice that it also fails in #72, so I guess it's not my fault?