xml attribute locations

[jurgenvinju]

• Using jsoup 1.17.1 which can track attribute locations
• minor refactoring for clarity

[jurgenvinju]

Thanks!

• Found a bug in the jsoup implementation, so I'm waiting for that fix and a release.
• If we ever want to lift these node to parse trees we also need the locations of the names of the attributes. So I'm thinking to extend the srcs map to map[str label, tuple[loc name, loc val] src]

[jurgenvinju]

See https://github.com/jhy/jsoup/issues/1933