HPCC-8849 QuerySet action commands should verify query exists

QuerySet action commands were sometimes calling lower level functions
that gracefully exited if the query did not exist.  The existence of
the specified query should always be verified and exceptions noted if
not.

Signed-off-by: Anthony Fishbeck <Anthony.Fishbeck@lexisnexis.com>
Merge pull request #4123 from afishbeck/ecl_unpublish_nonexisting8849

HPCC-8849 QuerySet action commands should verify query exists

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>