Bug 31435: (follow-up) Make kohaTable calls consistent

Bug 31435: (follow-up) Make kohaTable calls consistent

Our calls to instantiate a kohaTable from JS were inconsistent in how
they pass table_settings where no table_settings exist.

This patch replaces empty arrays and empty hashrefs with a consistent
'null' being passed to ake it clear we don't have any settings to pass
yet.

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Joonas Kylmälä <joonas.kylmala@iki.fi>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>