Consolidated approach for dumping generated sources

Using `drools.dump.dir = <String>` from KnowledgeBuilderConfiguration one can configure directory for dumping generated sources. New DRLs are generated out of decision tables and new java classes are generated out of DRLs into that location which makes it possible to analyze errors and have better understanding how code will actually work.

DSL parser uses different approach for dumping. It looks for `#result` switch and one need to configure logging for respective classes to see result of the parsing, see

org.drools.compiler.lang.dsl.DefaultExpander.expand(String drl)

Could it be consolidated approach used for all generated sources? Dump directory as a single place for all generated sources looks very handy. Could you please add respective logic for DefaultExpander to mimic

org.drools.compiler.builder.impl.KnowledgeBuilderImpl.generatedDrlToPackageDescr

and dump generated sources into one place if respective property set?