fix: include importer in illegal import error message

[teemingc]

closes #12550

Uses the resolveId hook to get the importer name before including it in the error message when loading the illegal import in the load hook.

However, I couldn't figure how to get this working for server only imports since those don't trigger the resolveId hook. (at least when I was running console logs to see if it did trigger it).

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[Conduitry]

It seems a bit more future-proof to me to instead maintain a map/lookup in the resolveId hook - and then in the load hook, check whether we happen to know what was importing this forbidden module - rather than making this specific to $env/ prefixes in both places. I realize you said that this doesn't seem to be working currently for server-only imports, but doing this in a more general way makes it easier to add that eventually when we figure it out.

[teemingc]

Thanks for the suggestion! I've replaced it with an import map.