Create task for generating modular runtime images with jlink

[zyxist]

Modular runtime images have been introduced in Java 9 as a new way for distributing Java apps as monolithic artifacts. The runtime image consists both of necessary JDK modules, and app modules, and it is optimized for increased startup times, and lower memory consumption.

Gradle Chainsaw Plugin could offer a task installRuntimeImage that would use jlink tool to generate the image from the dependencies.