Build Gradle Kotlin DSL 도입

[LeeOhHyung]

요구사항

Groovy로 되어있는 Build.gradle을 Kotlin DSL로 변경

Reference

1. https://woowabros.github.io/tools/2019/04/30/gradle-kotlin-dsl.html
2. https://seansation-blog.tistory.com/7