feat: Support use alias in dynamic import statements

[caoxiemeihao]

Description

1. chore: remove extension restrict

The extension not be necessary during vite serve phase, because the variables in import() can be correctly resolved at runtime

2. chroe: must be relative or root path

When i use alias in import(), it may get an absolute path like /User/name/project-path, which can work normally in the vite serve phase.

3. feat: dynamic import support alias

When I use import(), I hope I can also support alias, which is a very common case

e.g.

// source
import(`@/views/${component}`)

// transpile
import(`/User/name/project-path/views/${component}`)

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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[caoxiemeihao]

I write an plugin vite-plugin-dynamic-import for try enhance Vite builtin dynamic import.

[caoxiemeihao]

@bluwy Thanks for you help 😄