fix(vite): precisely check if files are in dirs

[danielroe]

Description

Discovered when debugging nuxt/nuxt#20446, if the root starts with the same path as something being resolved - for example if the root is /app and we are resolve the id /app.vue then we were not correctly prefixing the root directory to the incoming id.

This particular example is an edge case and probably only likely to occur in a docker container where a folder that high up the fs tree is used for the source files of a project.

However, this PR contains a raft of similar fixes where we were checking for a directory prefix but not that this prefix was delimited with a trailing slash. I suspect these will be hit rarely but occasionally.

Strictly speaking, only the change in packages/vite/src/node/plugins/resolve.ts is needed to resolve the issue I linked.

Additional context

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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[sapphi-red]

Thanks!

[patak-dev]

awesome ❤️