Reimplements yarn explain peer-requirements

[arcanis]

What's the problem this PR addresses?

I didn't update the yarn explain peer-requirements when I refactored the peer dependency warnings to report aggregates rather than independent entries. As a result, the reported hash doesn't work.

Fixes #5826

How did you fix it?

I reimplemented yarn explain peer-requirements to take those warnings into account. I also updated the output to use a more natural language which might help better understand the situation:

Note that I temporarily removed support for calling yarn explain peer-requirements on missing peer dependencies, as I'd like to take another look at those warnings in general (I noticed they aren't aggregated, but they probably should be too). Since they are fairly easy to understand by themselves, I don't feel like this is a significant regression.

Checklist

• I have read the Contributing Guide.

• I have set the packages that need to be released for my changes to be effective.

• I will check that all automated PR checks pass before the PR gets reviewed.