EclipseJavaUtil never evicts its cache when projects are deleted (or their classpath change)

When calling EclipseJavaUtil#findType(javaProject, qualifiedName) we hit a cache of ITypes using the project name has key.

Problem is, the cache is never updated if the project is deleted, or its classpath changes. This directly causes issues like JBIDE-12727, where we find an IType entry in a project's classpath which has the same name as a previously deleted project.

Everything is static in EclipseJavaUtil so we won't be able to implement IElementChangedListener directly. I believe you should had some new method in EclipseJavaUtil, like evict(key), that'd be called by an other IElementChangedListener, registered on plugin startup.