The <testsources> tag from <clover-setup> is not passed to groovyc

As in subject. As a consequence, the DefaultTestDetector is always used for Groovy code.

Fix:

Build proper TestDetector instance in GroovycSupport, which will be next serialized into InstrumentationConfig (instrumentation.ser file), so that next the Grover can deserialize it and pass to InstrumentingCodeVisitor.