Replace groovy gradle scripts with kotlin gradle scripts. As this
repository holds strictly Kotlin API, this commit ensures build scripts
are more familiar and standardised to the Kotlin community.

This commit adds Detekt https://detekt.dev/ to the repository. Detekt is
 a popular Kotlin linter and easy to integrate.

This commit also creates a baseline file, so to not make radical changes
 to the repository structure at once.

Finally, this commit sets up detekt.yml to execute detekt automatically
during pushes and pull requests and add its shield to the README

Signed-off-by: Leonardo Colman Lopes <dev@leonardo.colman.com.br>