HPCC-9187 Missing check for ecl-queries-copy --overwrite option

Signed-off-by: Anthony Fishbeck <Anthony.Fishbeck@lexisnexis.com>
Merge pull request #4294 from afishbeck/eclQueriesCopyOverwrite9187

HPCC-9187 Missing check for ecl-queries-copy --overwrite option

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>