feat: basic support of asset bundleless

[Timeless0911]

Summary

closes: #217

This pr implements basic support of assets in bundleless mode:

• Filter the glob resolved entry files based on the allowed extensions, inclulding js/css/json, asset extension is ignored from entry
• For bundleless external logic, we only check relative path import of js extensions
• Assets are processed by loader, so path is already correct and we do not need to redirect asset path [Feature]: Redirect in bundleless mode #140

We need to do #219 after this.

Related Links

Checklist

• Tests updated (or not required).
• Documentation updated (or not required).

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