- ensure all scraper functions have a `api.XYZ` version and a package-level convenience function
- isolate `the_api` to top-level convenience functions, in preparation for removal
- move a bunch of scraper functions around to be nearby their related functions
- new ErrLoginRequired
- remove obsolete APIv1 stuff (Feed, TweetDetail)
- rename scraper function GetUserFeedGraphqlFor => GetUserFeed
- fix go.mod Go version incorrectly claiming it's compatible with Go 1.16 (should be Go 1.17)