ENG-20456: Default to encoding a column as a String and CSV
ENG-20456: Default to encoding a column as a String and CSV

CSV encoder will quote and possibly escape values in the string
representation of a value, which is not desired. Instead use the string
encoder for handling a single column.

VoltDB/voltdb,VoltDB/voltdb,VoltDB/voltdb,VoltDB/voltdb,VoltDB/voltdb,VoltDB/voltdb,VoltDB/voltdb