Add maven modules discovery logs

[Riduidel]

Currently, the aadarchi GenerateDiagramsMojo task invokes MavenDetailInfererEnhancer, which discovers submodules. But if it doesn't, no error is output.

THe optimal behaviour would be at each endVisit to have a log message emitted counting the number of added elements.

For that, we need

1. @Inject Logger logger in variables
2. In each startVisit method, store in a property the element the number of children (something like aadarchi.internal.MavenDetailInfererEnhancer.children.count)
3. In each endVisit method, remove the property storing the number of children, remove this number from the current number of children.
4. If the remaining is >0, output a log message