Imported deps with test classifier should depend on test-scope dependencies

[bjchambers]

For example, if you pull in flink-streaming-java:jar:tests (needed for some testing helpers), it does not include the dependency on flink-runtime:jar:tests specified in the associated POM:

https://github.com/apache/flink/blob/master/flink-streaming-java/pom.xml#L81

The work around is to include flink-runtime:jar:tests in the dependencies.yaml, and then include it as a runtime_dep when you're using it. Ideally, the classifier being imported would adjust the scope of dependencies being scraped.