Provide goal "aggregate-cpd-no-fork"

### New feature, improvement proposal

The PMD plugin has a goal [`aggregate-pmd-no-fork`](https://maven.apache.org/plugins/maven-pmd-plugin/aggregate-pmd-no-fork-mojo.html) to generate a site report in an aggregator.

But the counterpart for CPD is missing.

Note: The "fork-using" ones (`aggregate-pmd` and `aggregate-cpd`) do exist.