[FIX] base: allow custom model to use SQL (materialized) views instead of table

closes odoo/odoo#41252

X-original-commit: f17d389c
Signed-off-by: Raphael Collet (rco) <rco@openerp.com>
Co-authored-by: Denis Ledoux <dle@odoo.com>
Co-authored-by: Raphael Collet <rco@odoo.com>