[FIX] fields: do not attempt to set foreign keys on views

Users sometimes define custom models on SQL views
e.g. @nseinlet
In such a case, Odoo should not attempt to create foreign keys
as it just cannot work on views.

This could prevent the migration of a database
with such a custom model using a view
when it attempted to fix the missing foreign keys
when updating the modules.

closes odoo/odoo#38988

X-original-commit: dfaea03d
Signed-off-by: Denis Ledoux (dle) <dle@odoo.com>