fix(plugin-vue): resolve sourcemap conflicts in build watch mode with cached modules

[edison1105]

Description

close #35

Additional context

---

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 PR Title 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.

[pkg-pr-new]

Open in Stackblitz

npm i https://pkg.pr.new/@vitejs/plugin-vue@505

npm i https://pkg.pr.new/@vitejs/plugin-vue-jsx@505

commit: 8204fce