HPCC-9547 packagemap-validate warning when library redefines query files

In Packagemaps if a query and a library redefine the same file
ecl-packagemap-validate should give a warning.

Signed-off-by: Anthony Fishbeck <anthony.fishbeck@lexisnexis.com>

Conflicts:
	common/workunit/referencedfilelist.cpp
	common/workunit/referencedfilelist.hpp
Merge pull request #4916 from afishbeck/pm-validate-library3

HPCC-9547 packagemap-validate warning when library redefines query files

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>