fix(plugin-vue): support scss/sass/less... hmr on custom template languages(fix #10677)

[Jevon617]

Fix #10677
Related PR: #6987

This PR is supplementary to #6987.

Description

Additional context

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

Before submitting the PR, please make sure you do the following

• Read the Contributing Guidelines.
• Read the Pull Request Guidelines and follow the Commit Convention.
• Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• Ideally, include relevant tests that fail without this PR but pass with it.

[bluwy]

I think we may want to discuss whether we're fine with exporting isCSSRequest or maybe the raw list of css extensions for this PR. But there are several usecases in the past where Svelte and Astro needs it too.

[benmccann]

I just noticed we could update this line if it were exposed:
https://github.com/sveltejs/kit/blob/0d4596340389233031588a77e478f9fb34a26d4e/packages/kit/src/exports/vite/dev/index.js#L18

[bluwy]

We discussed in the last meeting that exposing isCSSRequest is good. This PR needs a rebase and should be good to go.

[Jevon617]

I have merged the branch "main" into my branch.