HPCC-11754 Support copy of entire queryset from one environment to another

ecl copy-set //IP:PORT/&lt;src-queryset> &lt;dest-queryset> 

Also enhance behavior whenever copying queries from a remote environment:

Will try and reuse an existing local copy of the workunit, matching WUID,
hash, and dllCrc.

Otherwise try and reuse the WUID from the remote environment.

Also try and identify existing copies of the same query dll.

Signed-off-by: Anthony Fishbeck <anthony.fishbeck@lexisnexis.com>
if it is likely that wuid.length() > 0, but xml is NULL, it would be better to move the wuid test before the PTree create