Add Groovy programming language as overlay bundle

[ivandavidov]

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Note that Groovy depends on JVM. Groovy version 2.5.0 works with Java 7/8 and Groovy version 3.0 is designed to work with Java 9+.

By default MLL adds the latest stable packages and currently Java 10 is the latest stable Java. However, the latest stable Groovy package is for version 2.5. Adding Groovy in MLL at this point will require to add the latest bleeding edge Groovy version.