HPCC-12411 Allow compressor used in DISTRIBUTe to be configurable

HPCC-12411 Allow compressor used in DISTRIBUTe to be configurable
    
Signed-off-by: Jake Smith <jake.smith@lexisnexis.com>
Is there a way of saying no compressor?  Some of the code checks for expander, but I think it is always non-null.