Bug 32334: (QA follow-up) Improve finding schema file

Bug 32334: (QA follow-up) Improve finding schema file

Adds a schema parameter to the cmdline script now too.

Test plan:
Run sync_db_comments.pl with -schema file where file does not exist.
(On dev install) rename kohastructure.sql, try with[out] referring
to it using -schema. You could also use the standard path
intranet/cgi-bin/installer/data/mysql.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>