feat(core): show warnings on unused / redundant package extensions

[paul-soporan]

What's the problem this PR addresses?

Package extensions weren't validated in any way, which meant that they could easily get out of sync with the installed dependency tree without anybody noticing.

How did you fix it?

I've made it so that we emit warnings at the end of the resolution step (we can only know which package extensions are used once we resolve all packages) on:

• unused package extensions - happens when a package extension selector doesn't match any installed package
• redundant package extensions - happens when things would have the same behavior both with and without the extension

I've also fixed a weird bug with boolean values being loaded as strings from the configuration files and the lockfile - I've ranted enough about it on Discord where you can find more details.

You can see how it looks in this poorly-cropped screenshot below:

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.

[paul-soporan]

I think it makes more sense to only report user-provided and non-redundant extensions inside our telemetry collection.

[arcanis]

I think it might actually make a lot of sense to report the redundant builtins, since it means we can remove them during the next major. Wdyt?

[paul-soporan]

I have a few concerns:

• We can't tell which builtins are ours and which are registered by custom (possibly private) plugins. We can only distinguish between user-provided and not user-provided.
• Redundant builtins are relative to a project and its installed dependency tree, since a builtin can match multiple packages and can be active for some of them and redundant for others (e.g. if a dependency issue gets fixed in a newer version of a package).
• We'd have to report redundant builtins separately to be able to distinguish them inside the dashboard from active user-provided extensions.

[arcanis]

I think it might actually make a lot of sense to report the redundant builtins, since it means we can remove them during the next major. Wdyt?

[arcanis]

I made a diff refactoring slightly the rendering - in particular:

• The warnings are now printed in their own section. I saw your comment in feat(core): show warnings on unused / redundant package extensions  #2091 (comment), but I think it's important to put them aside because they are warnings that can usually be actioned right now, whereas the "invalid peer deps" are much trickier to address.

• I've tweaked the wording to directly reference the field names (rather than > / >> / etc). I feel like it makes the output quite a bit clearer, and decrease the amount of prior knowledge required.

• Also slightly tweaked the wording itself to try to explain what those warning mean.

• I've refactored the Report class to make them take responsibility for printing steps or not when they have no actual content. It's important, because this way people can disable the warnings using the new logFilter option and it'll have the right behaviour (previously the steps would still have been printed because install() would have had no idea that the messages would have been hidden).

• I've prevented packageExtensions from overwriting fields. It's technically breaking, but it wasn't meant to behave this way, and without this it'd be difficult to know which rules are used (for instance in our own repo there are two extraneous ones that didn't get catch because the peer dependencies had different ranges).

I think this looks really good! Your PR will be very useful to many 👍