refactor(2095): Refactor UnclosedResourcesProcessor

[slarse]

I got stuck trying to fix #540 because this processor is a bit complex. This PR completely refactors the UnclosedResourcesProcessor to make it easier to reason about.

[slarse]

Coverage on diff less than 100% as some conditions never evaluate to false (for example, we don't have any case where isAssignmentWithWriteToResolvedLocalVariable(parent) evaluates to false). But this preserves the semantics from before the refactoring: the coverage wasn't 100% before the refactoring either.

[slarse]

Just closing/opening to try to run CI again, Codecov is failing across all projects...

[slarse]

Codecov uploads are just failing across every single project... I'm sick of Codecov failing now, time to look for an alternative.

EDIT: I'm now ignoring Codecov upload failures in Sorald. I don't have time to replace it right now, we'll just have to do code coverage manually for the time being.

[fermadeiral]

@slarse, it looks good to me.

Should I merge?

[slarse]

@fermadeiral Yes, I've verified locally that coverage is acceptable, you can take my word for it :)