HPCC-12542 Add ECLWatch UI to call resetquerystats

On the Query Details page, a 'Reset' button is added to
send WsWorkunits an HTTP request of WUQuerysetQueryAction
with Action='ResetQueryStats'. After the request is
received, the WsWorkunits resets query stats using
control:resetquerystats.

Signed-off-by: wangkx <kevin.wang@lexisnexis.com>
You should check if Response + Result exists, before accessing it (lang.exists).