Dashboard to check compatibility of Java modules (Java 9+)

(ticket to track idea. Not decided to implement this yet)

Jeff found that we have multiple maven packages/modules providing the same package name which is not allowed in Java 9+ module system. Can BOM dashboard help to identify such problems across the Google Cloud libraries?

C.f. https://docs.oracle.com/javase/10/tools/jdeps.htm#JSWOR690

# Split Packages
The Java Module System page 66 explains split package problem
- When compilation, exported packages are checked for split packages.
- When launch, split packages are checked regardless of exported or not.

# Dependency Cycle
The Java Module System page 63 explains modules cannot have cyclic dependencies at launch.

> Resolution Cyclic dependences will not be supported at this time.
[Jigsaw spec on CyclicDependencies](http://openjdk.java.net/projects/jigsaw/spec/issues/#CyclicDependences)