HPCC-10651 Roxie dali cache ineffective on subfiles resolved via package

The cache was holding IResolvedFile objects, but the CResolvedFile for the
superfile was holding on to the IDistributedFile from the subfile, not the
IResolvedFile that contained it, so the subfiles kept getting added to the
cache then removed again as they were released.

Also adds some tracing.

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>