fix: improve handling of transformed content in hot updates for Vue files

[Jungzl]

Description

improve HMR handling for vue files that other plugins may have transformed
alternative for #306
fix: #301, unocss/unocss#3358

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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• Read the Contributing Guidelines.
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[huiliangShen]

LGTM