Moved batch-inserter configuration into Neo4JOutputModule of the insert-tool such that it is only used by index but not by the udg/ddg/argumentTainter tools as they need to perform lookups and thus require a cache.
Created a ConfigurationGenerator which gives out batch-inserter configurations based on the amount of memory available to the JVM. Also moved ReadWriteDBProvider to argumentTainter as that's the only tool using it.
Setting for 4GB machines and warning for people running joern on machines with too little RAM for big imports.