I've been looking at the new segment writer/segment uploader interfaces and implementations for use in a spark uploader and came across something I think could be improved. Seems like the FileBasedSegmentWriter pulls in pinot-core for exactly one class 'SegmentProcessorAvroUtils' ... which is only used currently by that class. I can't think of any good reason to pull in pinot core as a dependency for that plugin.

we should be able to remove that dependency from Pinot altogether