ProjectExample definition content mutates every time an example is created

Each ProjectExample instance, loaded from project example descriptors is mutated several times when actual exampled are created, such as https://github.com/jbosstools/jbosstools-central/blob/94cccaa18c185657c5c04a77f790942a671e7156/maven/plugins/org.jboss.tools.maven.project.examples/src/org/jboss/tools/maven/project/examples/ImportMavenProjectExampleDelegate.java#L171.

This prevents us from mixing for instance maven projects with non maven projects, since we lose all expected project names

The example definition and the actual example set per the user choices should be split, using the concept of a working copy (similar to what is done for launchconfigurations or runtimes)