fix(cli/import_map): Don't statically error on dynamic unmapped bare specifiers

[nayeemrmn]

Fixes #10168.
Fixes #10615.
Fixes #10616.

[bartlomieju]

I'm not entirely sure about this change - it seems to start deviating from the spec algorithm, but on the other hands none of the WPT fail so I guess it's okay.

[nayeemrmn]

Which part deviates from the spec algorithm? The two important changes are:

1. Structured import map errors (https://github.com/denoland/deno/pull/10618/files#diff-fba55433053f0ea5eef635f4d576f13beea8b8091c1d692f3513e46e4715e0d3L17-R20).
2. Solidifying Module::parse(), which doesn't error on ModuleResolutionError::ImportPrefixMissing, to also not error on its equivalent ImportMapError::UnmappedBareSpecifier (https://github.com/denoland/deno/pull/10618/files#diff-8439fae0dccaa5fecd30e137ceb78680f3b7884c1ae74a5f7c649f5273abf3e2L384-R391). This was the cause of the bug. I don't think it correlates with any spec.

All other changes are 1-to-1 simplifications e.g. the ImportMap::resolve() never returns None, so the Option is removed from its return type.

[bartlomieju]

Which part deviates from the spec algorithm? The two important changes are:

1. Structured import map errors (https://github.com/denoland/deno/pull/10618/files#diff-fba55433053f0ea5eef635f4d576f13beea8b8091c1d692f3513e46e4715e0d3L17-R20).
2. Solidifying Module::parse(), which doesn't error on ModuleResolutionError::ImportPrefixMissing, to also not error on its equivalent ImportMapError::UnmappedBareSpecifier (https://github.com/denoland/deno/pull/10618/files#diff-8439fae0dccaa5fecd30e137ceb78680f3b7884c1ae74a5f7c649f5273abf3e2L384-R391). This was the cause of the bug. I don't think it correlates with any spec.

All other changes are 1-to-1 simplifications e.g. the ImportMap::resolve() never returns None, so the Option is removed from its return type.

@nayeemrmn I see, somehow I thought spec required to return null/None when the resolution fails, but it seems you're just unifying the behavior.

LGTM then, I will let @kitsonk take a look before landing

[kitsonk]

Sorry, for some reason this was missing from my todo list... I will look at first thing tomorrow my time.

[kitsonk]

LGTM