Using kotlin-dsl for readable gradle script and easy navigation

In meanwhile, I would love to contribute to this repo and refactor current gradle into Kotlin-DSL. But, if there's anyone already refactor it into Kotlin-DSL might want to do a PR here

* https://github.com/andromax-gits-indonesia-org/gradle-kotlin-dsl-migration-guide
* https://github.com/mochadwi/android-social-app/tree/master/buildSrc/src/main/kotlin