maven-source-plugin should support goal source:test-jar (install:install should also install the generated test-source-jar)

In the maven-sourec-plugin I missed the possibility source:test-jar as in the the maven-jar-plugin jar:test-jar.

At the moment it is hard work to insert the wished source test-jar in the repository (gnerating and install)

I have seen that the source code is prepared to generate the test source jar.
It seems to me that the only thing that is missing the switch to call the generator of test-jar and extend the documentation.

If a xyz-version-test-sources.jar is generated the maven-install.plugin should have the possiblity to install the generated source in the local repository.