fix: remove library module name in vue wrapper build

[jwlee1108]

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Description

This PR is to fix vue-chart build script. When @toast-ui/vue-chart is imported in the version before the change, the chart is contained in an toastui object.

• When we write code below

  import tui from '@toast-ui/vue-chart;
  console.log(tui);

  

Related to #686

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Thank you for your contribution to TOAST UI product. 🎉 😘 ✨

[dongsik-yoo]

리뷰 완료합니다. 수고하셨습니다.

[lja1018]

리뷰완료합니다.

[adhrinae]

리뷰 완료합니다.

[js87zz]

늦었지만 리뷰 완료합니다~!