Add module graph

[shathor]

Is it possible to bring back the module graphs that were shown in the JDK 9 JavaDoc?

This would be helpful to get the overall structure of JavaFX modules. E.g. when adding a dependency to the artifact "javafx-controls" will also transitively get me "javafx-base" (I assume?). It would also be beneficial if we'd see on what JDK modules each eventually relies on. So we don't have to use jlink to figure that out. E.g. for "javafx.web"