Add warnings option for explain peer-requirements

[BasixKOR]

What's the problem this PR addresses?

Adresses #6329.

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How did you fix it?

Add an option called --warnings and changed the behaviour of explainPeerRequirements to not print met peer requirements when the option is enabled,

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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.

[BasixKOR]

Some notes:

• I don't mind bikeshedding on a flag name or variable name, please suggest better names as you see fit.
• Do you think it is suitable to show warnings-only by default? I personally think it's reasonable but I kept it disabled by default since that would be a breaking change.

[clemyan]

As I have said in #6329 (comment), the problem with this approach is that the flag is simply ignored in yarn explain peer-requirements --warnings p00000 and that can be confusing.

I don't mind it as a short-term solution but I think we still need to figure out a long-term solution

Resolved

[BasixKOR]

Thanks for the reference to #6329, I've updated the issue I opened to point there. While I do agree showing the unmet peer requirements would be more desirable it would be a breaqking change. I think adding this flag for the meantime makes sense as long as we can work on the solution for (potential) Yarn v5.