core: Move fkvalidator.sh to tools/dbutils

fkvalidator uses SPs that should also be moved to the tools/dbscripts
directory.

Since the fkvalidator is used from the installer in the pre-upgrade
step, it will fail if those SPs are not found.

Change-Id: Ib4211b8ff2ab00c85d9f73bb4e7338324017878a
Signed-off-by: Eli Mesika <emesika@redhat.com>
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=912305