Bug 34979: Add unit test for comparing YAMl files with sysprefs.sql

Bug 34979: Add unit test for comparing YAMl files with sysprefs.sql

The unit tests will help to detect any discrepancies
and missing entries in the YAML and sysprefs.sql files.

To test:
* Apply only this patch
* prove -v t/db_dependent/check_sysprefs.t
* It will fail.
* Apply other patches
* Run database update
* Re-run test. It should pass now.
* Recreate your database or reset_all with patches applied.
* System preferences should be installed correctly.
* Test should still pass.

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>