This adds mvn and gradle fallbacks for projects where no Maven Wrapper or Gradle Wrapper is present.

This was tested with 5 simple test projects. (mvn, mvnw, gradle, gradle-kts, gradlew each with a main class, a test class and inner tests)

I took the liberty to adjust the message when no build tooling is found from "No build system found" to "No build tool found" as these are rather tools than complete "build systems".

EDIT: Updated to support Kotlin DSL (build.gradle.kts) based projects.