[WIP] Customize the export method of specific files

[Copilot]

Thanks for assigning this issue to me. I'm starting to work on it and will keep this PR's description up to date as I form a plan and make progress.

Original issue description:

For example, for .vue files, we allow exporting in this way export { default as Component } from 'Component.vue', it may look like this in the configuration

{
  '*.vue': {
    all: true,
    default: 'filename' // 'filename' | 'camel-filename' | 'capitalize-filename'
  }
}

it will get an export result like

export * from 'Component.vue'
export { default as Component } from 'Component.vue'

Fixes #22.

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