chore: remove import-meta-resolve

[Rich-Harris]

I learned from @pi0 in #13513 that import.meta.resolve no longer takes a second argument, meaning it can't be used for resolving a peer dependency relative to the current working directory. As such, we won't be able to migrate to it once it's supported everywhere we care about.

So unless we intend to keep import-meta-resolve around forever, we should just get rid of it now. I don't think we need to use a library for this (especially since we know which packages we're using this with, and so don't need to deal with any weird edge cases) — we can just implement the logic ourselves. This PR adds a resolve_peer function which is duplicated between packages/kit and packages/adapter-auto, since a little duplication is better than faffing around with a more convoluted package structure.

Closes #13528 (which has the 3.0 milestone, but this isn't a breaking change so we can do it immediately)

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The changes in this PR will be included in the next version bump.

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@sveltejs/adapter-auto	Patch
@sveltejs/kit	Patch

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[benmccann]

This logic exists in package-manager-detector (used by svelte CLI, changesets, and publint). It might be good to use here too as it supports Deno, which I notice we're not supporting here

[Rich-Harris]

maybe we could just follow this PR up with one that adds Deno support? Or is there a reason to strongly prefer adding the dependency?

[benmccann]

yeah, we probably could. I think the main reason to possibly prefer the dependency is that getting some of the commands right for Deno has been maddeningly difficult. even now there's an issue open that the install command is not working correctly: antfu-collective/package-manager-detector#51