feat: allow package subpaths in ssr.noExternal

[cyco130]

Description

I often need to package a Vite plugin along with some runtime library and some piece of code that requires processing by Vite. I want the runtime entry to be externalized for SSR but the entry that requires processing (maybe a virtual module) not to be externalized. Without this PR, it is not easily possible because ssr.external accepts subpaths but ssr.noExternal doesn't. Furthermore, a package name in ssr.external is interpreted as applying to all subpaths of that package. This PR modifies the algorithm to check if the ID is in ssr.noExternal before applying the previous rule.

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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