Implement POI's suggested workaround for their classloader issue

The Apache POI folks do not want to change their classloader setup, unfortunately. But they have provided a hook for overriding the class loader in 3.16 and up here:

org.apache.poi.POIXMLTypeLoader.setClassLoader(ClassLoader cl)

This sets the classloader into a ThreadLocal. So there would be a rather clunky workaround that would have the TikaExtractor set the POI class loader before all tika-parser requests.

It only makes sense to do this if there is no plan to solve this for real.