HPCC-12037 virtual(logicalfilename) missing implicit scope

For a relative logical filename (i.e. without ~ prefix), the
implicit workunit scope was not being prepended to the front of
the logical filename in a virtual(logicalfilename) field output.

Signed-off-by: Jake Smith <jake.smith@lexisnexis.com>
Merge pull request #6312 from jakesmith/hpcc-12037

HPCC-12037 virtual(logicalfilename) missing implicit scope

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>